Automatically-activated hand-supportable laser scanning bar code symbol reading system with omnidirectional and unidirectional scanning modes in addition to a data transmission activation switch

ABSTRACT

A dual mode laser-based bar code symbol reading device having a hand-supportable housing with a light transmission aperture through which visible light can exit and enter the hand-supportable housing. A laser scanning engine, disposed within the hand-supportable housing, is controlled to selectively operate in either an omni-directional scan mode or a single line scan mode. In the omni-directional scan mode, the laser scanning engine projects an omni-directional scan pattern through the light transmission aperture, detects and decodes bar code symbols on objects passing through the omni-directional scan pattern, and produces symbol character data representative of decoded bar code symbols. In the single-line scan mode, the laser scanning engine projects a single line scan pattern through the light transmission aperture and detects and decodes bar code symbols on objects passing through the single line scan pattern, and produces symbol character data representative of decoded bar code symbols. A manually-actuatable data transmission switch, integrated with said hand-supportable housing, produces an activation signal in response to the manual-actuation of the data transmission switch. A data transmission subsystem, disposed in the hand-supportable housing, operates under control of control circuitry to communicate the symbol character data produced by the laser scanning engine to a host device operably coupled to the bar code symbol reading device. The control circuitry enables communication of symbol character data produced by the laser scanning engine in the single line scan mode of operation to the host device in response to the activation signal produced by the data transmission switch, and the control circuitry enables communication of symbol character data produced by the laser scanning engine in the omni-directional scan mode of operation to the host device irrespective of the activation signal produced by the data transmission switch. Preferably, the bar code symbol reading device is supported in a support stand and a mode selection means (e.g., hall sensor and control circuitry) is integrated with the hand-supportable housing of the device. The mode selection means selectively operates the laser scanning engine of the device in either the omni-directional scan mode of operation or the single line scan mode of operation in response to placement of said hand-supportable housing in the support stand. This feature enables the device to automatically operate, when placed in the support stand, in the omni-directional scan mode of operation as a stationary hands-free projection scanner, and automatically operate, when removed from the support stand, in the single scan line mode of operation as a portable hand-held scanner. In addition, the laser scanning engine of the device preferably includes circuitry that operates in a preprogrammed set of operational states wherethrough the device automatically passes during each bar code symbol reading operation, the states including an object detection state (which may be omitted), a bar code presence detection state, and a bar code symbol reading state.

RELATED CASES

[0001] The present application is a continuation-in-part (CIP) of:co-pending U.S. patent application Ser. No. 09/204,176 filed Dec. 3,1998 (108-027USA000) and co-pending U.S. patent application Ser. No.09/452,976 filed Dec. 2, 1999 (108-078USA000). Each said patentapplication is assigned to and commonly owned by Metrologic Instruments,Inc. of Blackwood, N.J., and is incorporated herein by reference in itsentirety.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates generally to improvements inautomatic laser scanning bar code symbol reading systems, wherein laserscanning and bar code symbol reading operations are automaticallyinitiated in response to the automatic detection of objects and/or barcode symbols present thereon.

[0004] 2. Brief Description Of The Prior Art

[0005] Bar code symbols have become widely used in many environmentssuch as, for example, point-of-sale (POS) stations in retail stores andsupermarkets, inventory management document tracking, and diverse datacontrol applications. To meet the growing demands of this technologicalinnovation, bar code symbol readers of various types have been developedfor sending bar code symbols and producing symbol character data for useas input in automated data processing systems.

[0006] In general, prior art hand-held bar code symbol readers usinglaser scanning mechanisms can be classified into two major categories.

[0007] The first category of hand-held laser-based bar code symbolreaders includes lightweight hand-held laser scanners havingmanually-actuated trigger mechanisms for initiating laser scanning andbar code symbol reading operations. The user positions the hand-heldlaser scanner at a specified distance from the object bearing the barcode symbol, manually activates the scanner to initiate reading, andthen moves the scanner over other objects bearing bar code symbols to beread. Prior art bar code symbol readers illustrative of this firstcategory are disclosed in U.S. Pat. Nos.: 4,575,625; 4,845,349;4,825,057; 4,903,848; 5,107,100; 5,080,456; 5,047,617; 4,387,297;4,806,742; 5,021,641; 5,468,949; 5,180,904; 5,206,492; 4,593,186;5,247,162; 4,897,532; 5,250,792; 5,047,617; 4,835,374; 5,017,765;5,600,121; 5,149,950; and 4,409,470.

[0008] The second category of hand-held laser-based bar code symbolreaders includes lightweight hand-held laser scanners havingautomatically-activated (i.e. triggerless) mechanisms for initiatinglaser scanning and bar code symbol reading operations. The hand-heldlaser scanner is positioned at a specified distance from an objectbearing a bar code symbol, the presence of the object is automaticallydetected using an infrared (IR) light beam or a low-power laser lightbeam, the presence of the bar code symbol on the object is detectedusing a visible laser light beam, and thereafter the detected bar codesymbol is automatically scanned and decoded (i.e. read) to producesymbol character data representative of the read bar code symbol.Examples of laser-based bar code symbol reading systems belonging tothis second category are disclosed in U.S. Pat. Nos. 5,844,227;4,639,606; 4,933,538; 5,828,048; 5,828,049; 5,825,012; 5,808,285;5,796,091; 5,789,730; 5,789,731; 5,777,315; 5,767,501; 5,736,982;5,742,043; 5,528,024; 5,525,789; D-385,265; 5,484,992; 5,661,292;5,637,852; 5,468,951; 5,627,359; 5,424,525; 5,616,908; 5,591,953;5,340,971; 5,340,973; 5,557,093; 5,260,553.

[0009] Such automatically-activated laser scanning bar code symbolreaders perform aggressive bar code symbol reading operations that arewell suited for POS applications where the laser scanner is configuredas a fixed presentation scanner (where the scanner is fixed while thebar-coded objects are moved through the scanning field). However, suchaggressive bar code symbol reading operations may be problematic in someportable applications (where the scanner is moved or aimed onto abarcode label for reading), for example, when attempting to read aparticular bar code from a list of bar code symbols closely printed on abar code menu or like structure. In this situation, the scan line mayscan across two or more bar code symbols at the same time therebycausing an inadvertent bar code symbol reading error. Oftentimes, suchbar code symbol reading errors must be corrected at their time ofoccurrence, wasting valuable time and resources of the user.

[0010] In the fixed “presentation” mode of operation, because objectsare often swept through the scanning field in random orientations, it ispreferable to use an omni-directional scan pattern; however, suchomni-directional scan pattern exacerbates the menu reading problem asdescribed above.

[0011] U.S. Pat. Nos. 6,247,647; 5,962,838; and 5,719,385 describe barcode symbol reading devices having multiple line and single linescanning modes that potentially combat these problems. However, becausesuch devices fail to provide the user with adequate control over thedisposition of the bar code symbol reading process, such devices aresusceptible to the menu reading problem as described above when thedevice (operating in single line scan mode) is positioned at a largedistance from the object and the scan line is large due to the scanninggeometry of the scanner.

[0012] Thus, there is a great need in the art for an improved system andmethod of reading bar code symbols using automatically-activated laserscanning mechanisms capable of automatically reading bar code symbolsprinted on diverse types of objects including, but not limited to,printed bar code symbol menus.

OBJECTS AND SUMMARY OF THE INVENTION

[0013] Accordingly, it is a primary object of the present invention toprovide an improved device and method of reading bar code symbols usingan automatically-activated laser scanning mechanism while overcoming theabove described shortcomings and drawbacks of prior art devices andtechniques.

[0014] Another object of the present invention is to provide anautomatically-activated laser scanning bar code symbol reading deviceand method which provides the user with a greater degree of control overthe disposition of bar code symbol reading processes automaticallyinitiated to read bar code symbols printed on diverse types of objectsincluding, but not limited to, printed bar code symbol menus.

[0015] Another object of the present invention is to provide anautomatically-activated bar code symbol reading device comprising a barcode symbol reading mechanism contained within a hand-supportablehousing that is capable of operating in two different scan modes: in afirst scan mode, the bar code symbol reading mechanism automaticallygenerates an omni-directional visible laser scanning pattern forrepeatedly reading one or more bar code symbols on an object during abar code symbol reading cycle, and automatically generating a new symbolcharacter data string in response to each bar code symbol read thereby;in a second scan mode, the bar code symbol reading mechanismautomatically generates a single line visible laser scanning pattern forrepeatedly reading one or more bar code symbols on an object during abar code symbol reading cycle, and automatically generating a new symbolcharacter data string in response to each bar code symbol read thereby.

[0016] Another object of the present invention is to provide such anautomatically-activated laser scanning bar code symbol reading device,wherein the bar code symbol reading mechanism automatically enters thefirst “omni-directional” scan mode when the hand-supportable housing isplaced in a support stand (that supports the housing), and automaticallyenters the second “single-line” scan mode when the hand-supportablehousing is removed from the support stand.

[0017] Another object of the present invention is to provide anautomatically-activated bar code symbol reading device comprising amanually-actuatable data transmission control (activation) switch thatis capable of producing a control activation signal that enablescommunication of symbol character data (produced by the bar code symbolreading system) to a host system in an automatic manner.

[0018] Another object of the present invention is to provide such anautomatically-activated laser scanning bar code symbol reading device,wherein the control subsystem thereof enables the transmission ofproduced symbol character data to the associated host system or datastorage device, only when the data transmission control switch providedon the exterior of the scanner housing is manually actuated by the userduring a bar code symbol reading cycle.

[0019] Another object of the present invention is to provide such anautomatically-activated laser scanning bar code symbol reading device,wherein the bar code symbol reading cycle is visually signaled to theuser by a bar code symbol reading state indicator provided on thescanner housing.

[0020] Another object of the present invention is to provide aautomatically-activated bar code symbol reading device which comprises:(i) a hand-supportable housing, (ii) a preprogrammed set of operationalstates wherethrough the device automatically passes during each bar codesymbol reading operation, without requiring manual actuation of aswitch, trigger or like component within the system, and (iii) apreprogrammed symbol character data transmission state of operation intowhich the device is automatically induced in response tomanual-actuation of a data transmission control switch provided on theexterior of the housing of the bar code symbol reader.

[0021] Another object of the present invention is to provide such anautomatically-activated bar code symbol reading device, wherein thepreprogrammed set of operational states include an object detectionstate of operation, a bar code presence detection state of operation,and a bar code symbol reading state of operation, wherein each of thesestates of operation are automatically activated in response to theautomatic detection of predetermined conditions in the object detectionfield, bar code symbol detection field and/or bar code reading field ofthe device.

[0022] Another object of the present invention is to provide such anautomatically-activated bar code symbol reading device, wherein theobjection detection is carried out using either infrared (IR) signaltransmission/receiving technology, or low-power non-visible laser beamsignaling technology.

[0023] Another object of the present invention is to provide anautomatically-activated bar code symbol reading device comprising a setof color-encoded light sources provided on the exterior of the systemhousing for sequentially generating a set of visually-perceptible stateindication signals that visually indicate to the user the various statesof operation, wherethrough the device automatically passes during eachbar code symbol reading cycle.

[0024] Another object of the present invention is to provide such anautomatically-activated bar code symbol reading device, wherein the setof color-encoded state indicating light sources on the exterior of thehousing sequentially generate a visually-perceptible object detectionindication signal when the device is automatically induced into theobject detection state of operation, a visually-perceptible bar codesymbol presence detection indication signal when the device isautomatically induced into its bar code symbol detection state ofoperation, and a visually-perceptible bar code symbol read indicationsignal when the device is automatically induced into its bar code symbolreading state of operation.

[0025] A further object of the present invention is to provide such anautomatically-activated bar code symbol reading device, wherein thehand-supportable bar code symbol reading device can be used as either aportable hand-supported laser scanner in an automatic hands-on mode ofoperation having a manually-activated data transmission state ofoperation, or as a stationary laser projection scanner in an automatichands-free mode of operation having a automatically-activated datatransmission state of operation.

[0026] A further object of the present invention is to provide such anautomatically-activated bar code reading device, wherein a support standis provided for supporting the hand-supportable bar code symbol readingdevice in its automatic hands-free mode of operation and automaticallygenerating a data transmission control activation signal to enable theautomatically-activated data transmission state in this operationalmode.

[0027] A further object of the present invention is to provide anautomatically-activated bar code reading device wherein a visible laserlight source, scanning element and a plurality of stationary mirrorscooperate to produce an omni-directional scan pattern.

[0028] A further object of the present invention is to provide anautomatically-activated bar code reading device wherein a visible laserlight source, scanning element and a predetermined subset of a pluralityof stationary mirrors cooperate to produce a single line scan pattern.

[0029] A further object of the present invention is to provide such anautomatically-activated bar code reading device wherein the power (e.g.duty cycle) of the visible laser light is controlled to selectivelyenable the laser light source to produce normal laser light only whenthe light produced therefrom is directed by said scanning element ontothe predetermined subset of stationary mirrors.

[0030] A further object of the present invention is to provide such anautomatically-activated bar code reading device that derives timingsignals synchronized to a particular interval in the rotation cycle of arotating light directing element when the rotating light directingelement directs light produced from the laser light source onto thepredetermined subset of stationary mirrors.

[0031] A further object of the present invention is to provide such anautomatically-activated bar code reading device that derives such timingsignals from a position sensor integrated into a rotating portion of therotating light directing element.

[0032] A further object of the present invention is to provide such anautomatically-activated bar code reading device that derives such timingsignals a position indicating optical element mounted adjacent (or near)the perimeter of one of said stationary mirrors, such that the positionindicating optical element is illuminated by light produced from saidlaser light source when the rotating light directing element reaches apredetermined point in its rotation.

[0033] It is another object of the present invention to provide anautomatically-activated bar code symbol reading system with a mode ofoperation that permits the user to automatically read one or more barcode symbols on an object in a consecutive manner.

[0034] A further object of the present invention is to provide apoint-of-sale station incorporating the automatically-activated bar codesymbol reading system of the present invention.

[0035] Another object of the present invention is to provide a portable,fully automatic bar code symbol reading system which is compact, simpleto use and versatile.

[0036] Yet a further object of the present invention is to provide anovel method of reading bar code symbols using theautomatically-activated bar code symbol reading system of the presentinvention.

BRIEF DESCRIPTION OF THE DRAWINGS

[0037] For a fuller understanding of the Objects of the PresentInvention, the Detailed Description of the Illustrated Embodiments ofthe Present Invention should be read in conjunction with theaccompanying drawings, wherein:

[0038]FIG. 1A illustrates the omni-directional scan mode of operation ofan automatically-activated hand-holdable bar code symbol reading deviceaccording to the present invention, wherein a laser scanning engine 53produces an omni-directional laser scanning pattern (formingmultiple-scan lines) passing through light transmission window 168 forthe purpose of scanning bar code symbols on objects within a narrowlyconfined 3-D scanning volume 164, while preventing unintentionalscanning of bar code symbols on objects located outside thereof.

[0039]FIG. 1B illustrates the unidirectional scan mode of operation ofan automatically-activated hand-holdable bar code symbol reading deviceaccording to the present invention, wherein a laser scanning engine 53produces a uni-directional laser scanning pattern (forming a single scanline) passing through light transmission window 168 for the purpose ofscanning bar code symbols on objects within a one dimensional scanningfield 165, while preventing unintentional scanning of bar code symbolson objects located outside thereof.

[0040]FIG. 2A illustrates the bar code symbol reading operations of theautomatically-activated hand-holdable bar code symbol reading devicewhen operating in the omni-directional scan mode of operation of FIG.1A.

[0041]FIG. 2B illustrates the bar code symbol reading operations of theautomatically-activated hand-holdable bar code symbol reading devicewhen operating in the uni-directional scan mode of operation of FIG. 1B.

[0042]FIG. 3 illustrates a generalized system design of theautomatically-activated hand-holdable bar code symbol reading deviceaccording to the present invention, including an object detectionsubsystem 2; a laser-based bar code symbol detection subsystem 3; alaser-based bar code symbol reading subsystem 4; a data transmissionsubsystem 5; a state indication subsystem 6; a data transmissionactivation switch 155 integrated with the scanner housing in part orwhole; a mode-selection switch or sensor 7 integrated with the scannerhousing in part or whole; and a system control subsystem 8 operablyconnected to the other subsystems described above. In general, device151 has a number of preprogrammed operational states (or modes), namely:an Object Detection State; a Bar Code Symbol Detection State; a Bar CodeSymbol Reading State; and a Data Transmission State.

[0043]FIGS. 4A and 4B illustrate an exemplary laser scanning platformthat employs a mechanism that controls the power (e.g., duty cycle) of alaser light source to selectively produce an omni-directional scanpattern or the single line scan pattern.

[0044] FIGS. 4C and 4D1 and 4D2 illustrative exemplary mechanisms thatprovide synchronization of the power control cycle (e.g., duty cycle) ofthe laser light source to the particular interval in the rotation cycleof the rotating polygon when the rotating polygon directs the scanninglaser beam to the central stationary mirror of the platform of FIGS. 4Aand 4B.

[0045]FIGS. 5A, 5B, 5C and 5D illustrate an exemplaryautomatically-activated hand-holdable bar code symbol reading systemaccording to the present invention including an automatic (i.e., triggerless) hand-holdable bar code symbol reading device 151′ operablyassociated with a base unit 503 having a scanner support 504 pivotallyconnected thereto, for releasably supporting the automatic bar codesymbol reading device 151′ at any one of a number of positions above ofa counter surface at a Point of Sale (POS) station. The scanner support504 is particularly adapted for receiving and supporting thehand-holdable bar code symbol reading device 151′ without user support,thus providing a stationary, automatic hands-free mode of operation. Asshown in FIGS. 5C and 5D, the head portion 161 A of the device 151′continuously extends into contoured handle portion 161B at an obtuseangle α (which, in the illustrative embodiment, is about 115 degrees),and the mass balance of the device 151′ is particularly designed tominimize the torque imposed on the user's wrists and forearms whileusing the bar code symbol reading device in the hands-on mode ofoperation.

[0046]FIG. 6 illustrates an exemplary system design of anautomatically-activated hand-holdable bar code symbol reading device151′ according to the present invention, including a number ofcooperating components, namely: control circuitry 611A and a controlmodule 611B that cooperate to perform system control operations toeffectuate the system control; a scanning circuit 613 that drives theVLD and laser beam scanning mechanism (e.g., motor of rotating polygonof the laser scanning platform) to thereby produce an omni-directionalmultiple line scan (or uni-directional single line scan) of a visiblelaser beam; a scan photoreceiving circuit 615 for detecting laser lightreflected off a scanned bar code symbol and producing an electricalsignal D₁ indicative of the detected intensity; an analog-to-digital(A/D) conversion circuit 617 for converting analog scan data signal D₁into a corresponding digital scan data signal D₂; a bar code symbolpresence detection circuit 619 for processing digital scan data signalD₂ in order to automatically detect the digital data pattern of a barcode symbol on the detected object and produce control activation signalA₂; a symbol decoding module 621 for processing digital scan data signalD₂ so as to determine the data represented by the detected bar codesymbol, generate symbol character data representative thereof, andproduce activation control signal A₃; a data packet synthesis module 623for synthesizing a group of formatted data packets (that include thesymbol character data generated by the symbol decoding module); a datapacket transmission circuit 625 for transmitting the group of datapackets synthesized by the data packet synthesis module 623 to the baseunit 503 (for retransmission to the host device); means (e.g. an objectsensing circuit 627 and an object detection circuit 629) for producing afirst activation control signal indicative of the detection of an objectin at least a portion of the object detection field of the device; anSOS photoreceiving circuit 631 for detecting laser light directedthereto by positioning indicating optical element(s) (such as a lens andlight guide or mirror as described above) and deriving timing signalT_(SOS) that is synchronized thereto; a timing signal generator circuit633 that derives a timing signal T_(SLS) from the timing signal T_(SOS),wherein the timing signal T_(SLS) is synchronized to the time intervalwhen the laser beam (as redirected by the rotating polygon) provides theuni-directional single line scan (e.g., strikes the central stationarymirror 38C); a VLD duty cycle control circuit 635 that operates (undercontrol of the control circuitry 611A) in the uni-directional (singlescan line) scan mode of operation, to control the duty cycle of the VLDof the laser beam production module such that the laser beam is producedtherefrom only during those intervals when the laser beam (as redirectedby the rotating polygon 36) provides the uni-directional single linescan (e.g., strikes the central stationary mirror 38C); amanually-actuatable data transmission switch 637 for generating controlactivation signal A₄ in response to activation of the switch 637; a modeswitch 639 for generating control activation signal A₅ in response toactivation of the switch 639; state indications (e.g. LEDs) 170′ thatprovide a visible indication of the operating state (e.g., objectdetection state, a bar code symbol presence detection state, bar codesymbol reading state, and data transmission state) of the device 151′;and a power control circuit 641, operably coupled to the rechargeablebattery supply unit (not shown) of the device 151′, that automaticallycontrols (i.e. manages) the availability of battery power toelectrically-active components within the bar code symbol reading devicewhen the device is operated in its hands-on mode of operation (i.e.removed from the scanner support stand) under a predefined set ofoperating conditions.

[0047]FIG. 7A illustrates an example of the timing signal T_(SOS)produced by the SOS photoreceiving circuit of FIG. 6, including pulses(e.g., a pulse train), each corresponding to a single rotation of therotating polygon, that are synchronized to the time T₁ when the scanningbeam is incident on (or near) the trailing edge of the particular mirrorgroup (e.g., central stationary mirror 38C) that provides theunidirectional single scan line.

[0048]FIG. 7B illustrates an example of the timing signal T_(SLS)produced by the timing signal generator circuit of FIG. 6, includingpulses (e.g., a pulse train) each corresponding to a single rotation ofthe rotating polygon and each having a leading and trailing edgesynchronized to the time interval between T₂ and T₁ when the scanningbeam (as redirected by the rotating polygon) strikes the particularmirror group (e.g., central stationary mirror 38C) that provides theunidirectional single scan line.

[0049]FIG. 7C is an example of Boolean logic expressions thatselectively enable the VLD drive circuitry of the scanning circuit ofFIG. 6 to provide VLD duty cycle control. The first term providesenablement of the VLD drive circuitry in the uni-directional (singlescan line) scan mode of operation (which is dictated by the controlcircuitry 611A with signals E₁₀=1 and A₅=1). The second term providesthe enablement of the VLD drive circuitry in the omni-directional(multiple scan line) scan mode of operation (which is dictated by thecontrol circuitry 611A with signals E₁₀=1 and A₅=0).

[0050]FIG. 8 is a state diagram illustrating the various states that theautomatically-activated bar code reading device of the present inventionmay undergo during the course of its programmed operation.

[0051]FIGS. 9A, 9B, 9C and 9D, taken together, show a high level flowchart of an exemplary control process carried out by the controlsubsystem of the bar code reading device of FIG. 6 during the course ofits programmed operation.

DETAILED DESCRIPTION OF THE ILLUSTRATIVE EMBODIMENTS OF THE PRESENTINVENTION

[0052] Referring to the figures in the accompanying Drawings, thevarious illustrative embodiments of the automatically-activated laserscanning bar code symbol reading system of the present invention will bedescribed in great detail, wherein like elements will be indicated usinglike reference numerals.

[0053] Prior to detailing the various illustrative embodiments of thepresent invention, it will be helpful to first provide a brief overviewof the system and method thereof.

[0054] As illustrated in FIGS. 1A and 1B, the automatically-activatedhand-holdable bar code symbol reading device 151 of the presentinvention includes a hand-supportable housing 161 having a head portion161A that encloses a laser scanning bar code symbol reading engine 53that is capable of operating in an omni-directional scan mode ofoperation and in a unidirectional scan mode of operation.

[0055]FIG. 1A illustrates the omni-directional scan mode of operationwherein the engine 53 produces an omni-directional laser scanningpattern (forming multiple-scan lines) passing through light transmissionwindow 168 for the purpose of scanning bar code symbols on objectswithin a narrowly confined 3-D scanning volume 164, while preventingunintentional scanning of bar code symbols on objects located outsidethereof. After the successful reading of a bar code symbol by the engine53, symbol character data (corresponding to the same bar code symbol) isautomatically transmitted from the engine 53 to a host system (e.g.electronic cash register system, data collection device, or other datastorage/processing device, etc.) over a communication link therebetween(which, for example, may be a wireless data link or wired serial datalink (such as an RS-232 link or USB link) or a wired parallel data bus).The omnidirectional multiple line scan mode of operation is useful inapplications, such as point of sale systems, where the orientation ofthe object/bar code to be scanned may vary.

[0056]FIG. 1B illustrates the uni-directional scan mode of operationwherein the engine 53 produces a uni-directional laser scanning pattern(forming a single scan line) passing through light transmission window168 for the purpose of scanning bar code symbols on objects within a onedimensional scanning field 165, while preventing unintentional scanningof bar code symbols on objects located outside thereof. After thesuccessful reading of a bar code symbol by the engine 53 and the timelyactuation of data transmission activation switch 155, symbol characterdata (corresponding to the same bar code symbol) is transmitted from theengine 53 to the host system (e.g. electronic cash register system, datacollection device, or other data storage/processing device, etc.) overthe communication link therebetween. Such unidirectional single linescanning and manually activated data transmission is useful inapplications (such as applications that involve menus and/or catalogs)where multiple bar codes are located proximate to one another, and inapplications that use two-dimensional bar codes.

[0057] As shown in FIGS. 1A and 1B, a set of color-coded state indicatorlights 170 are preferably mounted on the head portion of the devicehousing 161A, for visually displaying the particular state in which thesystem resides at any instant of time. A more detailed description ofexemplary color-coding schemes are set forth below.

[0058]FIG. 2A illustrates the bar code symbol reading operations of thebar code symbol reading device 151 when operating in theomni-directional scan mode of operation of FIG. 1A. During such symbolreading operations, the bar code symbol reading engine 53 automaticallyproduces a visible onmi-directional (multiple line) laser scanningpattern for repeatedly reading one or more bar code symbols 1005 on anobject 1006, and automatically generates a symbol character data string1007 in response to a given bar code symbol read thereby. In general,the symbol reading operations performed by the engine 53 has apredetermined time extent controlled by one or more timers that areperiodically monitored during system operation.

[0059] During such bar code symbol reading operations, it is assumedthat user 1007 has visually aligned the visible omni-directional(multiple line) laser scanning pattern produced by the engine 53 with aparticular bar code symbol 1005 on an object (e.g. product, bar codemenu, etc.) 1006 so that the bar code symbol 1005 is scanned, detectedand decoded, thereby producing a bar code symbol character stringcorresponding thereto. Upon successful decoding of a given bar codesymbol, an indicator light (for example one of the indicator lights 170)on the hand-supportable housing 161 preferably is actively driven andthe bar code symbol character string 1007 corresponding to the given barcode symbol, schematically depicted as a directional-arrow structure, isautomatically transmitted to the host system.

[0060]FIG. 2B illustrates the bar code symbol reading operations of thebar code symbol reading device 151 when operating in the uni-directionalscan mode of operation of FIG. 1B. During such symbol readingoperations, the bar code symbol reading engine 53 automatically producesa visible uni-directional (single line) laser scanning pattern forrepeatedly reading one or more bar code symbols 1005 on an object 1006,and automatically generates a symbol character data string 1007 inresponse to a given bar code symbol read thereby. In general, the symbolreading operations performed by the engine 53 has a predetermined timeextent controlled by one or more timers that are periodically monitoredduring system operation.

[0061] During such bar code symbol reading operations, it is assumedthat user 1008 has visually aligned the visible uni-directional (singleline) laser scanning pattern produced by the engine 53 with a particularbar code symbol 1005 on an object (e.g. product, bar code menu, etc.)1006 so that the bar code symbol 1005 is scanned, detected and decoded.Each time a scanned bar code symbol is successfully read during a barcode symbol reading cycle, a new bar code symbol character string,schematically depicted as a circulating-arrow structure 1007, isproduced and an indicator light (for example one of the indicator lights170) on the hand-supportable housing 161 preferably is actively driven.As indicated at Block B, upon actuation of the data transmission switch155 during the bar code symbol reading operation, a data transmissioncontrol activation signal is internally produced, enabling the symbolcharacter data string 1007, schematically depicted as adirectional-arrow structure, to be selected and transmitted to the hostsystem. However, if the user 1008 does not actuate the data transmissionswitch 155 during the bar code symbol reading operation, the datatransmission control activation signal is not produced, and the symbolcharacter data string 1007 is not transmitted to the host system.

[0062] By virtue of the present invention, an automatically-activateddual-mode hand-supportable bar code symbol reader is provided that isselectively operated in either an omni-directional scan mode ofoperation or a uni-directional (single line) scan mode of operation, tothereby enable the reading of diverse types of bar code symbols on barcode menus, consumer products positioned in crowded POS environments,and other objects requiring automatic identification and/or informationaccess and processing.

[0063] Moreover, in the both the omni-directional and uni-directionalscan modes of operation, bar code symbol detection and bar code symbolreading operations are carried out in a fully automatic manner, withoutthe use of a manually-actuated trigger or like mechanism, as disclosed,for example, in U.S. Pat. Nos. 5,828,048; 5,828,049; 5,825,012;5,808,285; 5,796,091; 5,789,730; 5,789,731; 5,777,315; 5,767,501;5,736,482; 5,661,292; 5,627,359; 5,616,908; 5,591,953; 5,557,093;5,528,024; 5,525,798, 5,484,992; 5,468,951; 5,425,525; 5,240,971;5,340,973; 5,260,553; incorporated herein by reference.

[0064] A generalized system design of the automatically-activatedhand-holdable bar code symbol reading device 151 according to thepresent invention is shown in FIG. 3, including: an object detectionsubsystem 2; a laser-based bar code symbol detection subsystem 3; alaser-based bar code symbol reading subsystem 4; a data transmissionsubsystem 5; a state indication subsystem 6; a data transmissionactivation switch 155 integrated with the scanner housing in part orwhole; a mode-selection switch or sensor 7 integrated with the scannerhousing in part or whole; and a system control subsystem 8 operablyconnected to the other subsystems described above. In general, device151 has a number of preprogrammed operational states (or modes), namely:an Object Detection State; a Bar Code Symbol Detection State; a Bar CodeSymbol Reading State; and a Data Transmission State.

[0065] The object detection subsystem 2 operates in the Object DetectionState to automatically detect if an object exists within the objectdetection field (which is proximate to the scanning field of the device151) and automatically generate a first control activation signal A₁indicative thereof (for example, A₁=0 is indicative that an object hasnot been detected within the object detection field, and A₁=1 isindicative that an object has been detected within the object detectionfield). As shown in FIG. 3, the first control activation signal A₁ isprovided to the system control subsystem 8 for detection, analysis andprogrammed response. In general, the object detection subsystem 2 canutilize electromagnetic radiation or acoustical energy, either sensibleor non-sensible by the operator, to automatically detect if an objectexists within the object detection field.

[0066] For example, the object detection subsystem 2 may project apulsed beam of infrared light from the housing 161 into the objectdetection field, which is a three-dimensional volumetric expansespatially coincident with the pulsed infrared light beam. When an objectwithin the object detection field is illuminated by the pulsed infraredlight beam, infrared light reflected there from will be returned towardthe housing 161, where it can be detected to derive an indication thatan object exists within the object detection field. Details of anexemplary object detection subsystem 2 that implements this approach isdescribed in U.S. Pat. No. 5,789,730 to Rockstein et al, commonlyassigned to the assignee of the present invention, herein incorporatedby reference in its entirety.

[0067] Alternatively, the object detection subsystem 2 may project apulsed laser beam of visible light from the housing 161 into the objectdetections filed, which is a three-dimensional volumetric expansespatially coincident with the pulsed laser beam. When an object withinthe object detection field is illuminated by the pulsed laser beam,light reflected there from will be returned toward the housing 161,where it can be detected to derive an indication that an object existswithin the object detection field. Details of exemplary object detectionsubsystems that implement this approach is described in U.S. Pat. No.4,639,606 to Boles, et al, and U.S. Pat. No. 4,933,538 to Heiman, et al.herein incorporated by reference in their entirety.

[0068] Alternatively, the object detection subsystem 2 may projectultrasonic energy from the housing 161 into the object detection field,which is a three-dimensional volumetric expanse spatially coincidentwith such ultrasonic energy. When an object within the object detectionfield is illuminated by the ultrasonic energy, ultrasonic energyreflected there from will be returned toward the housing 161, where itcan be detected to derive an indication that an object exists within theobject detection field.

[0069] Alternatively, the object detection subsystem 2 may utilize apassive technique that utilizes ambient light to detect that an objectexists in the object detection field. More specifically, when an objectwithin the object detection field is illuminated by ambient light, lightreflected therefrom will be returned toward the housing 161, where itcan be detected to derive an indication that an object exists within theobject detection field. Details of exemplary object detection subsystemsthat implement this approach is described in U.S. Pat. No. 5,789,730 toRockstein et al, commonly assigned to the assignee of the presentinvention, incorporated by reference above in its entirety.

[0070] In addition, the object detection subsystem 2 may utilize twodifferent modes of object detection: a long range mode of objectdetection and a short range mode of object detection. Details ofexemplary object detection subsystems that implement this approach isdescribed in U.S. Pat. No. 5,789,730 to Rockstein et al, commonlyassigned to the assignee of the present invention, incorporated byreference above in its entirety.

[0071] The laser-based bar code symbol presence detection subsystem 3operates in the Bar Code Symbol Detect State to automatically scan thescanning field (with an onmi-directional multiple line scan pattern or auni-directional single line scan pattern) to detect if a bar code ispresent with the scanning field of the device 151, and automaticallygenerate a second control activation signal A₂ indicative thereof (forexample, A₂=0 is indicative that a bar code is not present within thescanning region, and A₂=1 is indicative that a bar code is presentwithin the scanning region). As shown in FIG. 3, the second controlactivation signal A₂ is provided to the system control subsystem 8 fordetection, analysis and programmed response. As described below indetail, a mode select sensor 7 generates a fifth control activationsignal A₅ which indicates if the device 151 is to operate in anomni-directional (multiple line) scan mode (e.g., A₅=0) or in auni-directional (single line) scan mode (e.g., A₅=1). This signal A₅ isprovided to the laser-based bar code symbol detection subsystem 3, whichselectively utilizes either an omni-directional multiple line scanpattern or a unidirectional single line scan pattern to detect if a barcode is present with the scanning field of the device 151 in responsebased upon the fifth control activation signal A₅. For example, thelaser-based bar code symbol detection subsystem 3 may utilize anomni-directional multiple line scan pattern to detect if a bar code ispresent with the scanning field of the device 151 in response to thesignal A₅=0, and utilize a uni-directional single line scan pattern todetect if a bar code is present with the scanning field of the device151 in response to the signal A₅=1.

[0072] The bar code symbol detection subsystem 3 does not carry out abar code symbol decoding process, but rather rapidly determines whetherthe received scan data signals represent a bar code symbol residingwithin the scan field. There are a number of ways in which to achievebar code symbol detection. For example, the bar code symbol detectionsubsystem 3 may detect the first and second borders of the bar codesymbol “envelope”. This is achieved by first processing a digital scandata signal to produce digital “count” and “sign” data. The digitalcount data is representative of the measured time interval (i.e.duration) of each signal level occurring between detected signal leveltransitions which occur in digitized scan data signal. The digital signdata, on the other hand, indicates whether the signal level betweendetected signal level transitions is either a logical “21”,representative of a space, or a logical “0”, representative of a barwithin a bar code symbol. Using the digital count and sign data, the barcode symbol detection subsystem 3 identifies the first and secondborders of the bar code envelope, and thereby determines whether or notthe envelope of a bar code symbol is represented by the scan datacollected from the scan field. When a bar code symbol envelope isdetected, the bar code symbol detection subsystem 3 automaticallygenerates a second control activation signal A₂=1, which is indicativethat a bar code is present within the scanning region.

[0073] The bar code symbol detection subsystem 3 may utilize twodifferent modes of bar code symbol detection, namely: a long-range modeof bar code symbol detection and a short-range mode of bar code symboldetection as taught in U.S. Pat. No. 5,789,730, incorporated byreference above in its entirety.

[0074] The laser-based bar code symbol reading subsystem 4 operates inthe Bar Code Symbol Reading State to automatically scan the scanningfield (with an omni-directional multiple line scan pattern or auni-directional single line scan pattern) to detect and decode bar codesymbols on objects therein, produce bar code symbol character datarepresentative of the detected and decoded bar code symbol, andautomatically generate a third control activation signal A₃ indicativeof a successful decoding operation (for example, A₃=0 is indicative thata successful decoding operation has not occurred, and A₃=1 is indicativethat a successful decoding operation has occurred). As shown in FIG. 3,the third control activation signal A₃ is provided to the system controlsubsystem 8 for detection, analysis and programmed response. The signalA₅ generated by the mode select sensor 7 is also provided to thelaser-based bar code symbol detection subsystem 3, which selectivelyutilizes either an omni-directional multiple line scan pattern or auni-directional single line scan pattern to detect and decode bar codesymbols on objects within the scanning field of the device 151 inresponse to the signal A₅. For example, the symbol detection subsystem 3may utilize an omni-directional multiple line scan pattern to detect anddecode bar code symbols in response to the signal A₅=0, and utilize aunidirectional single line scan pattern to detect and decode bar codesymbols in response to the signal A₅=1.

[0075] The data transmission subsystem 5 operates in the DataTransmission State to automatically transmit symbol character data(produced by the operation of the bar code symbol reading subsystem 4 inthe Bar Code Symbol Reading State as described above) to the host system(to which the bar code reading device 151 is connected) or to some otherdata storage and/or processing device. Preferably, the operation of thedata transmission system 5 in the Data Transmission State occurs whenthe system control subsystem 8 detects that either one of the followingtwo conditions have been satisfied:

[0076] i) generation of the third control activation signal (e.g., A₃=1)within a predetermined time period, indicative that the bar code symbolhas been read, and generation of data transmission control activationcontrol signal (e.g., A₄=1) produced from data transmission activationswitch 155 within a predetermined time frame, indicative that the userdesires the produced bar code symbol character data to be transmitted tothe host system or intended device; or

[0077] ii) generation of the third control activation signal (e.g.,A₃=1) within a predetermined time period, indicative that the bar codesymbol has been read, and generation of fifth control activation signalA₅ (e.g., A₅=0) indicative that device 151 is to operate inomni-directional (multiple line) scan mode.

[0078] Note that the mode-select sensor 7, when indicating that device151 is to operate in omni-directional (multiple line) scan mode (e.g.,A₅=0), effectively overrides the data transmission switch 155, enablingthe automatic transmission of bar code symbol character strings to thehost system.

[0079] Within the context of the system design shown in FIG. 3, theprimary function of the state-select sensor 7 is to generate the fifthcontrol activation signal A₅, which indicates if the device 151 is tooperate in an omni-directional (multiple line) scan mode (e.g., A₅=0) orin a unidirectional (single line) scan mode (e.g., A₅=1).

[0080] In the preferred embodiment of the present invention, thehand-holdable bar code symbol reading device 151 of the presentinvention operates in the omni-directional (multiple line) scan mode(e.g., A₅=0) as a hand-free presentation scanner whereby the operatorpasses objects and associated bar code symbols though the scanning fieldof the device 151 in order to automatically read the bar code symbolstherein and automatically transmit corresponding bar code symbolcharacter strings to the host system, and operates in theuni-directional (single line) scan mode (e.g., A₅=1) as a hands-onscanner whereby the operator positions the scanner so that an object andassociated bar code symbol passes though the scanning field of thedevice 151 in order to automatically read the bar code symbol thereinand then activate the transmission of the corresponding bar code symboldata string to the host computer upon timely manual activation of a datatransmission activation switch.

[0081] The state-select sensor 7 may utilize a manual or automatedmechanism (or both) in generating the fifth control activation signalA₅. The manual mechanism may include a manual two-state switch (e.g.,button) mounted into the housing 161 of the device 151. In an initialconfiguration, the manual switch generates and provides the controlsignal A₅=0. When the user first presses the manual switch, the manualswitch generates and provides the control signal A₅=1. And when the userpresses the manual switch a second time, the manual switch generates andprovides the control signal A₅=0. Similar to the operation of a pushbutton light switch, subsequent presses of the manual switch follow thistwo-state activation sequence: A₅=0 to A₅=1 back to A₅=0. The automaticmechanism may include a sensor that detects whether the hand-holdablebar code symbol reading device 151 has been placed within a supportstand (or placed on a countertop or like surface in those instanceswhere it has been designed to do so) and automatically generates thecontrol signal A₅ in response thereto. For example, the state-selectsensor 7 may automatically generate the signal A₅=0 upon detection thatthe hand-holdable bar code symbol reading device 151 has been placedwithin a support stand (or placed on a countertop or like surface inthose instances where it has been designed to do so), and automaticallygenerate the signal A₅=1 upon detection that the hand-holdable bar codesymbol reading device 151 has been removed from the support stand (orlifted off the countertop or like surface in those instances where ithas been designed to do so). A more detailed description of an exemplarystate-select sensor 7 that detects whether or not the hand-holdable barcode symbol reading device 151 has been placed within a support standand automatically generates fifth control activation signal A₅ inresponse thereto is described below with respect to Figure??.

[0082] Within the context of the system design shown in FIG. 3, thestate indication subsystem 6 produces visual indication (e.g.color-coded light) signals that are emitted from the scanner housing 161to inform the user of the current state of operation of the system (e.g.“blue” to indicate the object detection state, “red” to indicate the barcode detection state, “yellow” to indicate the bar code reading state,and “green” to indicate the symbol character data transmission state).As will be described in greater detail hereinafter, such stateindication signals provide the user with visual feedback on the statesof operation of the system, thereby improving the intuitiveness andfacility of operation of the system in diverse application environments.

[0083] Within the context of the system design shown in FIG. 3, thesystem control subsystem 8 performs the following primary functions: (i)automatically receiving control activation signals A₁, A₂, A₃, A₄ and A₅(ii) automatically generating enable signals E₁, E₂, E₃, E₄ and E₅ and(iii) automatically controlling the operation of the other subsystems inaccordance with a system control program carried out by the systemcontrol subsystem 8 during the various modes of system operation.

[0084] Initially, system control subsystem 8 provides enable signal E₁=1to the object detection subsystem 2. When an object is presented withinthe object detection field, the object is automatically detected by theobject detection subsystem 2. In response thereto, the object detectionsystem automatically generates a control activation signal A₁=1. Whencontrol activation signal A₁=1 is detected by the system controlsubsystem 8, it automatically activates the laser-based bar code symboldetection subsystem 3 by producing enable signal E₂. This causes thelaser-based bar code detection subsystem 3 to generate a laser scanningpattern (either an omni-directional multi-line scan pattern or auni-directional single line scan pattern depending on control activationsignal A₅) within the bar code detection field. When the laser scanningpattern scans a bar code symbol on the detected object, scan datasignals are produced therefrom, collected and processed to determinewhether a bar code symbol is present within the bar code symboldetection field. If the presence of a bar code symbol is detected, thenthe system control subsystem 8 automatically generates enable E₃ so asto activate the bar code symbol reading subsystem 4. In responsethereto, the laser-based bar code reading subsystem 4 automaticallygenerates a laser scanning pattern (either an omni-directionalmulti-line scan pattern or a unidirectional single line scan patterndepending on control activation signal A₅) within the bar code readingfield, scans the detected bar code symbol disposed therein, collectsscan data therefrom, decodes the detected bar code symbol, generatessymbol character data representative of the decoded bar code symbol, andbuffers the symbol character data in memory. If the detected bar codesymbol is read within a predetermined period of time, and themanually-activated data transmission switch 7A is depressed within apredetermined time frame established by the system control subsystem 8,then the system control subsystem 8 automatically activates the datatransmission subsystem 5 by producing enable signal E₅. In responsethereto, the data transmission subsystem 5 automatically transmits theproducedibuffered symbol character data to the host system (e.g.electronic cash register system, data collection device, or other datastorage/processing device, etc.) over a communication link therebetween(which, for example, may be a wireless data link or wired serial datalink (such as an RS-232 link or USB link) or a wired parallel data bus).

[0085] In general, the geometrical and optical characteristics of laserscanning patterns generated by the laser-based bar code symbol detectionsubsystem 3 and the laser-based bar code symbol reading subsystem 4 willdepend on the particular design the bar code symbol reading system ofthe present invention. In most applications, the laser scanning patternsgenerated within the bar code detection and reading fields will besubstantially congruent, and if not substantially congruent, thenarranged so that the bar code symbol reading field spatially-overlapsthe bar code symbol detection field to improve the scanning efficiencyof the system.

[0086] By virtue of the novel system control architecture, the user ispermitted to read bar code symbols utilizing an omni-directionalmulti-line scanning pattern or a unidirectional single line scanningpattern in a highly intuitive manner, wherein object detection, bar codedetection, and bar code symbol reading are carried out in an automaticmanner while data transmission of decoded symbol character data to thehost device in the uni-directional scanning mode is enabled bymanual-actuation of a switch, button or like device located on theexterior of the hand-supportable scanner housing.

[0087] In the preferred embodiment, a visual state indicator is providedon the scanner housing for visually indicating that a bar code symbolhas been successfully read in a fully-automatic manner, and that thesystem is ready for data transmission enablement to the host system orlike device in the uni-directional single line scanning mode (or thatthe system is (or has) performed data transmission to the host system orlike device in the omni-directional multiple line scanning mode). In theuni-directional single line scanning mode, when the visual indicatorindicates that a bar code symbol is being read and decoded symbolcharacter data is being generated, the user need only depress the datatransmission activation switch on the scanner housing within apre-allotted time frame to send the corresponding symbol character datato the host system or like device. Failure to depress the datatransmission switch within the pre-allotted time frame results in therenot being any symbol character data transmission to the host system.

[0088] Preferably, the laser-based bar code symbol detection subsystem 3and the laser-based bar code symbol reading subsystem 4 share a commonlaser scanning platform that is capable of selectively producing anomni-directional multiple line scan pattern or a uni-directional singleline scan pattern. A variety of scanning platforms may be alternativelyused to selectively produce such omni-directional and single line scanpatterns. Generally, these platforms employ a laser diode, the lightfrom which is focused and collimated to form a scanning beam. A scanningmechanism (such as a multi-faceted rotating mirror or rotatingholographic disk) directs the scanning beam to a first set of lightfolding mirrors to produce an omni-directional scan pattern, and directsthe scanning beam to a second set of light folding mirrors to produce asingle line scan pattern. Reflected laser light that returns back alongthe outgoing optical path is collected and directed to a detector, whichgenerates electrical signals whose amplitude corresponds to theintensity of the returned light directed thereto. Notably, the scanningmechanism can be realized in a variety of different ways. Thus, the term“scanning mechanism” as used herein is understood as any means formoving, steering, swinging or directing the path of a light beam throughspace during system operation for the purpose of obtaining informationrelating to an object and/or a bar code symbol.

[0089] Various mechanisms may be provided that enable the laser scanningplatform to selectively produce the omni-directional scan pattern orsingle line scan pattern, including the following:

[0090] i) selectively moving the first and second set of light foldingmirrors to spatially arrange either the first or second set of mirrorsinto operating position;

[0091] ii) movement of an optical control element into the optical pathof the scanning beam between the laser diode and the rotating mirror;when activated, the optical control element causes the scanning beam tobe directed to the second set of light folding mirrors (or the first setof light folding mirrors); and

[0092] iii) selectively moving the rotating mirror so that is inoperating position with respect to either the first or second set oflight folding mirrors.

[0093] An alternative mechanism controls the duty cycle of the laserdiode to thereby produce either the omni-directional scan pattern or thesingle line scan pattern. Such a mechanism is suitable forconfigurations where the second set of light folding mirrors (which isused to produce the single scan line) is a subset of the first set oflight folding mirrors (which is used to produce the omni-directionalscan pattern). In this configuration, by turning the laser diode oncontinuously, the rotating mirror directs the scanning beam to the firstset of light folding mirrors to produce the omni-directional scanpattern. By turning the laser diode on only during those intervals whenthe scanning beam strikes the second set of light folding mirrors, therotating mirror directs the scanning beam to the second set of lightfolding mirrors to produce the single line scan pattern. Thisalternative mechanism requires that the duty cycle (on/off cycle) of thelaser diode be synchronized to a particular interval in the rotationcycle of the rotating mirror (or rotating holographic disk) wherein therotating mirror directs the scanning beam to the second set of lightfolding mirrors.

[0094] Such synchronization may be derived from a position sensor (suchas a hall sensor), integrated into the rotating shaft (or other portion)of the rotating mirror (or rotating holographic disk), that generates anelectrical signal when the rotating mirror (or rotating holographicdisk) reaches a predetermined point (such as a start-of-scan position)in its rotation. Alternatively, such synchronization may be derived froma position indicating optical element (e.g., mirror or lens), which ispreferably mounted adjacent (or near) the perimeter of one of the lightfolding mirrors, such that the position indicating optical element isilluminated by the scanning beam when the rotating mirror (or rotatingholographic disk) reaches a predetermined point (such as a start-of-scanposition) in its rotation. The position indicating optical element maybe a mirror that directs the illumination of the scanning beam incidentthereon to a position indicating optical detector (which generates anelectrical signal whose amplitude corresponds to the intensity of lightincident thereon). Alternatively, the position indicating opticalelement may be a light collecting lens that is operably coupled to alight guide (such as a fiber optic bundle) that directs the illuminationof the scanning beam incident thereon to a position indicating opticaldetector (which generates an electrical signal whose amplitudecorresponds to the intensity of light incident thereon).

[0095]FIGS. 4A and 4B illustrate an exemplary laser scanning platformthat employs a mechanism that controls the duty cycle of a laser lightsource (e.g., laser diode) to selectively produce an omni-directionalscan pattern or the single line scan pattern. As shown in FIG. 4A, thelaser scanning platform 53′ comprises an assembly of subcomponentsassembled upon an optical bench 34 with respect to a centrallongitudinal reference plane 35. The optical bench is mounted to thehousing 161′ of the device 151′ by posts 42. This subcomponent assemblyincludes a scanning polygon 36 having four light reflective surfaces(e.g., facets) 36A, 36B, 36C and 36D, each disposed at an tilt angle βwith respect to the rotational axis of the polygon as shown in FIG. 5A.An electrical motor is mounted on the optical bench 34 and has arotatable shaft on which polygon 36 is mounted for rotation therewith.An array of stationary mirrors 38A, 38B, 38C, 38D and 38E is fixedlymounted with supports (not shown) to the optical bench 34 at twist andbend angles α, θ as shown in FIGS. 4A and 5B.

[0096] As shown in FIG. 4B, a laser beam production module 39 is fixedlymounted above the rotating polygon 36 with supports (not shown) andproduces a laser beam having a circularized beam cross-section andessentially free of astigmatism along its length of propagation. Thelaser beam production module 39 may be realized in a variety of ways.Preferably, it comprises a visible laser diode for producing a visiblelaser beam, and associated optics for circularizing the laser beam andeliminating astigmatism therefrom along its direction of propagation.For example, the associated optics may include an aspheric collimatinglens, a beam circularizing prism, and a holographic light diffractivegrating configured in such a manner that the abovedescribed functionsare realized during laser beam production. The manner in which such alaser beam production module can be constructed without the use ofaperture stops is taught in WIPO Publication WO9957579A2 entitled“DOE-Based Systems and Devices for Producing Laser Beams Having ModifiedBeam Characteristics”, published commonly assigned to the assignee ofthe present invention, herein incorporated by reference in its entirety.

[0097] In the omni-directional scan mode of operation, the duty cycle ofthe laser light source of the laser beam production module is controlledso that the laser beam is continuously produced therefrom and directedto rotating polygon 36, which cooperates with the full array ofstationary mirrors 38A, 38B, 38C, 38D and 38E to produce anomni-directional scan pattern that passes through transmission window168′.

[0098] In the uni-directional (single scan line) scan mode of operation,the duty cycle of the laser light source of the laser beam productionmodule is controlled so that the laser beam is produced therefrom onlyduring those intervals when the laser beam (as redirected by therotating polygon 36) strikes the central stationary mirror 38C, therebyproducing a uni-directional single line scan pattern that passes throughtransmission window 168′.

[0099] The particular parameters (and associated geometric model) usedto configure the optical components of the laser scanning platform aredescribed in detail in U.S. Pat. No. 5,844,227 to Schmidt et al.,commonly assigned to the assignee of the present invention, andincorporated by reference above in its entirety.

[0100] As shown in FIG. 4B, an analog signal processing board 40 isfixedly mounted over the rotating polygon 36 with supports (not shown),and carries one or more photodetector 41 (e.g., silicon photosensor(s))that detects reflected laser light and producing analog scan datasignals in addition to analog signal processing control circuits 42 (notshown) for performing various functions, including analog scan datasignal processing. In addition, the analog signal processing board 40preferably includes visible laser diode drive circuitry (not shown),motor drive circuitry (not shown), object sensing circuitry (e.g., aninfra-red light source, such as an infra-red LED, associated drivecircuitry, and infra-red light detection circuitry) and associatedobject detect circuitry, the functions of which are described in greaterdetail hereinafter.

[0101] A light collecting mirror 43 is disposed at a height above thecentral stationary mirror 38C and collects returning light raysreflected off the rotating polygon 36 and focuses the same onto thephotodetector 41. A beam directing surface 44, realized as a flat mirrormounted on the light collecting mirror 43, directs the laser beam fromthe laser beam production module 39 to the rotating polygon 36.

[0102] The uni-directional (single scan line) scan mode of operationrequires that the duty cycle (on/off cycle) of the laser light source ofthe laser beam production module 39 be synchronized to the particularinterval in the rotation cycle of the rotating polygon 36 wherein therotating polygon 36 directs the scanning laser beam to the centralstationary mirror 38C. FIGS. 4C and 4D1 and 4D2 illustrative alternativeconfigurations that provide such synchronization.

[0103] As shown in FIG. 4C, a position indicating lens 46 is mountedbetween the perimeter of stationary mirrors 38D and 38C such that theposition indicating lens 46 is illuminated by the scanning beam when therotating polygon 36 reaches a predetermined point (denoted start-of-scanposition) in its rotation. The positioning indicating lens 46 isoperably coupled to a light guide 47 (such as a fiber optic bundle) thatdirects the illumination of the laser beam incident thereon to aposition indicating optical detector 48 (which generates an electricalsignal whose amplitude corresponds to the intensity of light incidentthereon). Timing signals that are synchronized to the time interval whenthe laser beam (as redirected by the rotating polygon 36) strikes thecentral stationary mirror 38C are derived from the electrical signalsgenerated by detector 48. In the uni-directional (single scan line) scanmode of operation, such timing signals are used to control the dutycycle of the laser light source of the laser beam production module 39such that the laser beam is produced therefrom only during thoseintervals when the laser beam (as redirected by the rotating polygon 36)strikes the central stationary mirror 38C.

[0104] As shown in 4D1 and 4D2, a position indicating mirror 49 ismounted between the perimeter of stationary mirrors 38D and 38C suchthat the position indicating mirror 49 is illuminated by the scanningbeam when the rotating polygon 36 reaches a predetermined point (denotedstart-of-scan position) in its rotation. The positioning indicatingmirror 49 is oriented such that it directs the illumination of the laserbeam incident thereon along a position indicating reference axis 50(which is offset with respect to the central reference axis 35 as shown)to position indicating optical detector 48 (which generates anelectrical signal whose amplitude corresponds to the intensity of lightincident thereon). Timing signals (that are synchronized to the timeinterval when the laser beam (as redirected by the rotating polygon 36)strikes the central stationary mirror 38C) are derived from theelectrical signals generated by detector 48. In the unidirectional(single scan line) scan mode of operation, such timing signals are usedto control the duty cycle of the laser light source of the laser beamproduction module 39 such that the laser beam is produced therefrom onlyduring those intervals when the laser beam (as redirected by therotating polygon 36) strikes the central stationary mirror 38C.

[0105] Alternatively, such synchronization may be derived from aposition sensor (such as a hall sensor), integrated into the rotatingshaft (or other portion) of the rotating polygon 36, that generates anelectrical signal when the rotating mirror (or rotating holographicdisk) reaches a predetermined point (such as a start-of-scan position)in its rotation.

[0106] The structure and functionalities of the system design of FIG. 3as described above are shown in greater detail in the system embodimentof FIGS. 5A through 9F. As shown in FIG. 5A, an automatic bar codesymbol reading system 501 of the illustrative embodiment of the presentinvention comprises an automatically-activated (i.e., trigger less)hand-holdable bar code symbol reading device 151′ operably associatedwith a base unit 503 having a scanner support 504 pivotally connectedthereto, for releasably supporting the automatic bar code symbol readingdevice 151′ at any one of a number of positions above of a countersurface at a Point of Sale (POS) station. In the preferred embodiment,the bar code symbol reading device 151′ is operably coupled with its thebase unit 503 by way of a one way wireless communication linktherebetween, and the base unit 503 is operably coupled with a hostsystem (e.g., electronic cash register system, data collection device,etc.) by way of a two way wired communication link (such as a serialcommunication link over a communications cable). In this preferredembodiment, bar code symbol data generated by device 151′ iscommunicated over the wireless communication link to the base unit 503,which forwards the data to the host system over the two way wiredcommunications link. Alternatively, the bar code symbol reading device151′ may be operably coupled directly with the host system by way of atwo way wireless (or wired) communication link. In this alternativeembodiment, bar code symbol data generated by device 151′ iscommunicated over the wireless (or wired) link to the host system.

[0107] In this illustrative embodiment, electrical power from a lowvoltage direct current (DC) power supply (not shown) is provided to thebase unit 503. Notably, this DC power supply can be realized in hostcomputer system or as a separate DC power supply adapter pluggable intoa conventional 3-prong electrical socket. Such electric power isoperably coupled to a rechargeable battery power supply unit 20 that iscontained primarily within the handle portion of the bar code symbolreading device 151′ in order to energize the electrical andelectro-optical components within the device 15 1′. The details of therechargeable battery power supply unit 20 is described in U.S. Pat. No.5,844,227 to Schmidt et al.

[0108] As illustrated in FIGS. 5A and 5B, the scanner support 504 isparticularly adapted for receiving and supporting the hand-holdable barcode symbol reading device 151′ without user support, thus providing astationary, automatic hands-free mode of operation. The base unit 503can be realized as a compact stand for support upon a countertopsurface, or can be realized as a support mount for verticalwall-mounting. In either configuration, the function of the scannerstand 504 is to support the device 151′ in one or more positions above aworkspace (which may be a counter surface in POS applications). In thepreferred embodiment, the base unit 503 contains electronic circuitryrealized on a PC board for carrying out various types of functions,namely: reception of electrical power from the host system and couplingelectrical power to the rechargeable battery contained within the device151′; reception of bar code symbol character data (e.g., data packets)transmitted from the device 151′, and processing the same for datarecovery; generation of acoustical and/or optical acknowledgementsignals; and forwarding of received bar code symbol character data tothe host system.

[0109] As shown in FIG. 5B, preferably the scanner stand 504 ispivotally supported with respect to the base unit 503 by way of pivotpins (one shown as 522B). In order to releasably pivot (and hold) thestand 504 relative to the base 503 in any one of a number of providedscanning positions, a releasable stand-locking mechanism may beprovided, the details of which is described in U.S. Pat. No. 5,844,227to Schmidt et al.

[0110] As illustrated in FIGS. 5C and 5D, the head portion 161A of thedevice 151′ continuously extends into contoured handle portion 161B atan obtuse angle a (which, in the illustrative embodiment, is about 115degrees). It is understood, however, that in other embodiments obtuseangle a may be in the range of about 100 to about 150 degrees. Asillustrated in FIG. 5C, the mass balance of the device 151′ isparticularly designed so that when the device is held within the user'shand, the index finger of the user is disposed beneath the head portion161A of the housing, and provides a pivot point about which there issubstantially zero torque acting upon the device, preventing it fromrotating in either direction about the index finger. Instead, theresultant force distribution acting upon the user's hand is aligned inthe direction of gravitational forces, as indicted in FIG. 5C. Theeffect of this mass-balanced scanner design is to minimize the torqueimposed on the user's wrists and forearms while using the bar codesymbol reading device in the hands-on mode of operation. This, in turn,minimizes the amount of energy which the user must expend duringhands-on scanning operations, thereby reducing wrist and arm fatigue andincreasing worker productivity. In addition to the above advantages, thehand-supportable housing hereof is sculptured (i.e., form-fitted) to thehuman hand so that automatic hands-on scanning is rendered easy andeffortless. Also, the ergonomic housing design eliminates the risks ofmusculoskeletal disorders, such as carpal tunnel syndrome, which canresult from repeated biomechanical stress commonly associated withpointing prior art gun-shaped scanners at bar code symbols, andsqueezing a trigger to activate the laser scanning beam, and thenreleasing the trigger.

[0111] In this illustrative embodiment, the bar code symbol readingdevice 151′ includes the laser scanning platform (described above withrespect to FIGS. 4A to 4D2) mounted within its housing by way ofresiliently securing shock-mounting support posts to correspondingmounting holes formed within the optical bench 35 using rubber grommetsand screws. The details of this shock absorbing mounting mechanismsdescribed in U.S. Pat. No. 5,844,227 to Schmidt et al. Moreover, thehousing of the device 151′ is preferably realizes as a five-piecesplit-housing construction, the details of which is described in U.S.Pat. No. 5,844,227 to Schmidt et al.

[0112]FIG. 6 illustrates an exemplary system design of the hand-holdablebar code symbol reading system 151′ including a number of cooperatingcomponents, namely: control circuitry 611A and a control module 611Bthat cooperate to perform system control operations to effectuate thesystem control as described below in more detail with reference to FIGS.8 through 9D; a scanning circuit 613 that drives the VLD and laser beamscanning mechanism (e.g., motor of rotating polygon of the laserscanning platform) to thereby produce an omni-directional multiple linescan (or unidirectional single line scan) of a visible laser beam; ascan photoreceiving circuit 615 for detecting laser light reflected offa scanned bar code symbol and producing an electrical signal D₁indicative of the detected intensity; an analog-to-digital (A/D)conversion circuit 617 for converting analog scan data signal D₁ into acorresponding digital scan data signal D₂; a bar code symbol presencedetection circuit 619 for processing digital scan data signal D₂ inorder to automatically detect the digital data pattern of a bar codesymbol on the detected object and produce control activation signal A₂;a symbol decoding module 621 for processing digital scan data signal D₂so as to determine the data represented by the detected bar code symbol,generate symbol character data representative thereof, and produceactivation control signal A₃; a data packet synthesis module 623 forsynthesizing a group of formatted data packets (that include the symbolcharacter data generated by the symbol decoding module); a data packettransmission circuit 625 for transmitting the group of data packetssynthesized by the data packet synthesis module 623 to the base unit 503(for retransmission to the host device); means (e.g. an object sensingcircuit 627 and an object detection circuit 629) for producing a firstactivation control signal indicative of the detection of an object in atleast a portion of the object detection field of the device; an SOSphotoreceiving circuit 631 for detecting laser light directed thereto bypositioning indicating optical element(s) (such as a lens and lightguide or mirror as described above) and deriving timing signal T_(SOS)that is synchronized thereto; a timing signal generator circuit 633 thatderives a timing signal T_(SLS) from the timing signal T_(SOS), whereinthe timing signal T_(SLS) is synchronized to the time interval when thelaser beam (as redirected by the rotating polygon) provides theuni-directional single line scan (e.g., strikes the central stationarymirror 38C); a VLD duty cycle control circuit 635 that operates (undercontrol of the control circuitry 611A) in the unidirectional (singlescan line) scan mode of operation, to control the duty cycle of the VLDof the laser beam production module such that the laser beam is producedtherefrom only during those intervals when the laser beam (as redirectedby the rotating polygon 36) provides the uni-directional single linescan (e.g., strikes the central stationary mirror 38C); amanually-actuatable data transmission switch 637 for generating controlactivation signal A₄ in response to activation of the switch 637; a modeswitch 639 for generating control activation signal A₅ in response toactivation of the switch 639; state indications (e.g. LEDs) 170′ thatprovide a visible indication of the operating state (e.g., objectdetection state, a bar code symbol presence detection state, bar codesymbol reading state, and data transmission state) of the device 151′;and a power control circuit 641, operably coupled to the rechargeablebattery supply unit (not shown) of the device 151′, that automaticallycontrols (i.e. manages) the availability of battery power toelectrically-active components within the bar code symbol reading devicewhen the device is operated in its hands-on mode of operation (i.e.removed from the scanner support stand) under a predefined set ofoperating conditions.

[0113] The control circuitry 611A, which preferably includes RC timingnetworks (e.g. timers) and logic, operates under control of the controlmodule 611B to perform system control operations inactivating/deactivating the object detection circuit 307 (e.g., bygenerating enable signal E₁=1/E₁=0, respectively);activating/deactivating scan photoreceiving circuit 615, A/D conversioncircuit 617, the SOS photoreceiving circuit 631, timing signal generatorcircuit 633, VLD duty cycle control circuit 635, and the scan mechanismdrive control of the scanning circuit 613 ((e.g., by generating enablesignal E₁₀=1/E₁₀=0, respectively), and activating/deactivating the barcode symbol presence detection circuit 619 (e.g., by generating enablesignal E₂=1/E₂=0, respectively). The control circuitry 611A performssuch system control operations in response to the control activationsignals A₁ and A₂ provided thereto by the object detect circuitry 629and the bar code symbol presence detection circuitry 619, respectively.Exemplary implementations of such control circuitry 611A is described indetail in U.S. Pat. No. 6,283,375 to Wilz, Sr. et al., hereinincorporated by reference in its entirety.

[0114] The control module 611B, which is preferably realized using aprogrammable device (such as a microprocessor (or microcontroller)having accessible program memory and buffer memory and external timingcircuitry) operates to perform system control operations in controllingthe operation of the first control circuitry 611A,activating/deactivating the bar code symbol reading module 621 (e.g., bygenerating enable signal E₃=1/E₃=0, respectively),activating/deactivating the data packet synthesis module 623 (e.g., bygenerating enable signal E₄=1/E₄=0, respectively),activating/deactivating the data packet transmission circuit 625 (e.g.,by generating enable signal E₅=1/E₅=0, respectively). The control module611B performs such system control operations in response to the controlactivation signals A₃, A₄ and A₅ provided thereto by the bar code symbolreading module 621, the data transmission switch 637 and the mode selectswitch 639, respectively.

[0115] In the illustrative embodiment, scan photoreceiving circuit 615generally comprises one or more photodetector(s) (e.g. a siliconphotosensor) for detecting laser light focused thereon by the lightcollection optics of the scanning platform. In response to the reflectedlaser light focused onto the photodetector(s), the photodetector(s)produce an analog electrical signal which is proportional to theintensity of the detected laser light. This analog signal issubsequently amplified by a preamplifier to produce analog scan datasignal D₁. In short, the laser scanning circuit 613 and scanphotoreceiving circuit 615 cooperate to generate analog scan datasignals D₁ from the scanning field (i.e. bar code detection and readingfields), over time intervals specified by the control circuitry 611Aand/or control module 611B (e.g., time intervals when such componentsare activated by enable signal E₁₀=1). In addition, an optical filterhaving transmission characteristics tuned to the characteristicwavelength range of the light source used for scanning may be mounted infront of the photodetector(s) of the scan photoreceiving circuit 615 asdescribed below in detail. This optical configuration improves thesignal-to-noise ratio of the analog scan signal D₁ produced by the scanphotoreceiving circuit 615.

[0116] The analog scan data signal D₁ is provided as input to A/Dconversion circuit 617 that operates over time intervals specified bythe control circuitry 611A and/or control module 611B (e.g., timeintervals when the A/D conversion circuit 617 is activated by enablesignal E₁₀=1) in a manner well known in the art to process analog scandata signal D₁ to provide a digital scan data signal D₂, which has awaveform that resembles a pulse width modulated signal, where thelogical “1” signal levels represent spaces of the scanned bar codesymbol and the logical “0” signal levels represent bars of the scannedbar code symbol. The A/D conversion circuit 617 can be realized usingany conventional A/D conversion technique well known in the art.Digitized scan data signal D₂ is then provided as input to bar codesymbol presence detection circuit 619 and bar code symbol reading module621 for use in performing particular functions required during the barcode symbol reading process of the present invention.

[0117] In accordance with the present invention, the purpose of objectdetection circuit 629 is to produce a first control activation signalA₁=1 upon determining that an object (e.g. product, document, etc.) ispresent within the object detection field of the bar code symbol readingdevice 151′ over time intervals specified by the control circuitry 611Aand/or control module 611B (e.g., time intervals when the objectdetection circuit 629 is activated by enable signal E₁=1). In theillustrative embodiment automatic object detection is employed. It isunderstood, however, that “passive” techniques may be used withacceptable results. In the illustrative embodiment, object sensingcircuit 627 comprises an IR LED driven by an IR transmitter drivecircuit, and an IR phototransistor (or photodiode) activated by an IRreceive biasing circuit. These components are arranged and mounted onthe PC board so as to provide an object detection field that spatiallyencompasses the laser scanning plane. When activated, the objectdetection circuit 629 produces an enable signal IR DR which is providedto the IR transmitter drive circuit. The signal produced from IRphototransistor, identified as IR Receive, is provided as input signalto the object detection circuit 629 for signal processing that detectswhether an object is present within the object detection field. A moredetailed description of exemplary signal processing mechanisms forobject detection is set forth in U.S. Pat. No. 6,283,375 to Wilz Sr. etal. In the illustrative embodiment, IR LED generates a 900 nanometersignal that is pulsed at the rate of 1.0 kHz when the object detectioncircuit 629 is enabled by enable signal El produced from controlcircuitry 611A. Preferably, the duty cycle of such pulsed IR light isless than 1.0% in order to keep the average current consumption verylow. Alternately, the bar code symbol reading device 151′ can be readilyadapted to utilize ultrasonic energy for object detection whereby thereflection of ultrasonic energy off an object in the object detectionfield is detected and signals corresponding thereto are processed asdescribed in U.S. Pat. No. 6,283,375 to Wilz Sr. et al.

[0118] The primary purpose of bar code symbol presence detection circuit619 is to determine whether a bar code symbol is present in (or absentfrom) the bar code symbol detection field of the device 151′ over timeintervals specified by the control circuitry 611A and/or control module611B (e.g., time intervals when the bar code symbol presence detectioncircuit 619 is activated by enable signal E₂=1). In the illustrativeembodiment, bar code symbol detection circuit 619 indirectly detects thepresence of a bar code in the bar code symbol detection field bydetecting a bar code symbol “envelope”. In the illustrative embodiment,a bar code symbol envelope is deemed present in the bar code symboldetection field upon detecting a corresponding digital pulse sequence indigital signal D₂ which is produced by A/D conversion circuit 617. Thisdigital pulse sequence detection process is achieved by counting thenumber of digital pulse transitions (i.e. falling pulse edges) thatoccur in digital scan data signal D₂ within a predetermined time period.A more detailed description of exemplary signal processing mechanismsfor detecting a bar code symbol “envelope” is set forth in U.S. Pat. No.6,283,375 to Wilz Sr. et al.

[0119] The bar code symbol reading module 621, which is preferablyrealized using a programmable device (such as a microprocessor (ormicrocontroller) having accessible program memory and buffer memory andexternal timing circuitry), operates over time intervals specified bythe control module 611B (e.g., time intervals when the bar code symbolreading module is activated by enable signal E₃=1) to process, scan lineby scan line, the stream of digital scan data contained in the signal D₂in an attempt to decode a bar code symbol therein. Upon successfuldecoding of a bar code symbol, the bar code symbol reading moduleproduces symbol character data (representative of the decoded bar codesymbol and typically in ASCII format).

[0120] The data packet synthesis module 623 operates over time intervalsspecified by the control module 611B (e.g., time intervals when the datapacket synthesis module is activated by enable signal E₄=1) tosynthesize a group of data packets that encode the symbol character dataproduced by the bar code symbol reading module 621 for subsequenttransmission to the base unit 503 by way of data packet transmissioncircuit 625. The construction of the data packet synthesis module 623and data transmission circuit 625 will vary from embodiment toembodiment, depending on the type of data communication protocol beingused in the particular embodiment of the bar code symbol reading device151′.

[0121] The data transmission circuit 625 operates over time intervalsspecified by the control module 611B (e.g., time intervals when the datatransmission circuit 625 is activated by enable signal E₅=1) to transmitthe data packets produced by the data packet synthesis module 623 to thebase unit 503, which forwards such data to the host device over acommunication link therebetween. A more detailed description of theoperation of the communication interfaces between the bar code symbolreading device 151′ and base unit 503 and between the base unit 503 andthe host device is set forth in U.S. Pat. No. 6,283,375 and in U.S.patent application Ser. No. (Attorney Docket No. 108-141USA000),entitled “Bar Code Symbol Reading Device Having Intelligent DataCommunication Interface To A Host System”, filed on Sep. 27,2001,commonly assigned to Assignee of the Present Invention and hereinincorporated by reference in its entirety.

[0122] In the illustrative embodiment, power control circuitry 641 isconnected in series between the rechargeable battery (not shown) of thedevice 151′ and a power distribution circuit that provides electricalpower to the electrical components of the device 151′. The function ofthe power control circuitry 641 is to automatically control (i.e.manage) the availability of battery power to electrically-activecomponents within the bar code symbol reading device 151′ under apredefined set of operating conditions. The power control circuitry 641includes a resettable timer that controls the availability of batterypower (if the rechargeable battery is charged) to electrically-activecomponents within the bar code symbol reading device 151′. Morespecifically, upon reset, the timer specifies a predetermined timeinterval over which battery power is provided to electrically-activecomponents within the bar code symbol reading device 151′. Afterexpiration of the predetermined time interval (if the timer has not beenreset), battery power is unavailable to (i.e., electrically isolatedfrom) the electrically-active components within the bar code symbolreading device 151′. There are three different power switching eventswhich reset the timer to thereby maintain the availability of batterypower (if the rechargeable battery is charged) to theelectrically-active components within the bar code symbol reading device151′. The first power switching event comprises actuation ofmanually-actuatable power-reset switch (not shown), which may bespring-biased push-type button/switch (ormechanical/electromechanical/electronic sensor) mounted on the exteriorof the scanner housing. The second power switching event comprisesplacing the handle portion of the scanner housing within the recess ofthe scanner support stand hereof, whereby mode-select sensor 639 (e.g.,Hall-effect sensor) disposed within the handle of the housing detectsmagnetic flux produced from permanent magnet 640 mounted within thescanner support stand recess, as shown in FIG. 5B. The third powerswitching event comprises successfully reading a bar code symbol whereinthe bar code symbol reading module 621 produces control activationsignal A₃=1. A more detailed description of such power control circuitryis set forth in U.S. Pat. No. 5,844,227 to Schmidt et al. incorporatedby reference above in its entirety. In this illustrative embodiment, inthe automatic hand-held mode of operation, the bar code symbol readingdevice will automatically transition into power conserving operation(wherein battery power (if the rechargeable battery is charged) is notavailable to the electrically-active components within the bar codesymbol reading device 151′) upon the expiration of the resettable timer.To return to normal power-on operations (wherein battery power (if therechargeable battery is charged) is made available to theelectrically-active components within the bar code symbol reading device151′), the user is required to activate the power-reset switch.Advantageously, such operations provide for automatic conservation ofthe battery power stored in the rechargeable battery, thereby extendingthe operational lifetime of the bar code symbol reading device in thehandheld mode of operation.

[0123] The primary purpose of the SOS photoreceiving circuit 631 is todetect laser light directed thereto by positioning indicating opticalelement(s) of the scanning platform (such as a lens and light guide ormirror as described above) and to derive a timing signal T_(SOS) that issynchronized thereto. As the rotating polygon rotates, the scanning beamis directed across each stationary mirror from the mirror's leading edgeto the mirror's trailing edge. For example, the clockwise rotation ofthe rotating mirror 36 in FIG. 4D2 causes the scanning beam to bedirected across the central stationary mirror 38C from its leading edge61 to its trailing edge 63. In the illustrative embodiments describedabove with respect to FIGS. 4C and 4D1 and 4D2, the positioningindicating optical element(s) of the scanning platform (such as a lensand light guide or mirror) is preferably positioned at (or near) thetrailing edge of the particular mirror group (e.g., the trailing edge 63of central stationary mirror 38C as shown in FIG. 4D2) that provides theuni-directional single scan line as the rotating polygon rotates andredirects the scanning beam thereto. The SOS photoreceiving circuit 631generally comprises one or more photodetector(s) (e.g. a siliconphotosensor) for detecting the laser light focused thereon and producingan analog electrical signal which is proportional to the intensity ofthe detected laser light. This analog signal is supplied to circuitrythat generates a timing signal T_(SOS) having pulses (e.g., a pulsetrain), each corresponding to a single rotation of the rotating polygon,that are synchronized to the incidence of the scanning beam on (or near)the trailing edge of the particular mirror group (e.g., the trailingedge 63 of central stationary mirror 38C) that provides theunidirectional single scan line (as the rotating polygon rotates andredirects the scanning beam thereto). An example of the timing signalT_(SOS) produced by the SOS photoreceiving circuit 631 is shown in FIG.7A including pulses (e.g., a pulse train), each corresponding to asingle rotation of the rotating polygon, that are synchronized to thetime T₁ when the scanning beam is incident on (or near) the trailingedge of the particular mirror group (e.g., the trailing edge 63 of thecentral stationary mirror 38C) that provides the unidirectional singlescan line.

[0124] In an alternate embodiment, the rotating mirror 36 may be rotatedin a counterclockwise sense (not shown), which causes the scanning beamto be directed across the central stationary mirror 38C from edge 63 toedge 61. In this illustrative embodiment, the positioning indicatingoptical element(s) of the scanning platform (such as a lens and lightguide or mirror) is preferably positioned at (or near) the edge 61 ofcentral stationary mirror 38C, which provides the uni-directional singlescan line as the rotating polygon rotates and redirects the scanningbeam thereto.

[0125] The primary purpose of the timing signal generator circuit 633 isto derive a timing signal T_(SLS) from the timing signal T_(SOS),wherein the timing signal T_(SLS) is synchronized to the time intervalwhen the scanning beam (as redirected by the rotating polygon) strikesthe particular mirror group (e.g., central stationary mirror 38C) thatprovides the uni-directional single scan line as the rotating polygonrotates and redirects the scanning beam thereto. Preferably, the timingsignal T_(SLS) provides pulses (e.g., a pulse train), each correspondingto a single rotation of the rotating polygon and each having a leadingand trailing edge synchronized to the time interval when the scanningbeam (as redirected by the rotating polygon) strikes the particularmirror group (e.g., central stationary mirror 38C) that provides theunidirectional single scan line (as the rotating polygon rotates andredirects the scanning beam thereto). An example of the timing signalT_(SLS) produced by the timing signal generator circuit 633 is shown inFIG. 7B.

[0126] The VLD duty cycle control circuit 635 operates, under control ofthe control circuitry 611A in the uni-directional (single scan line)scan mode of operation, to control the duty cycle of the VLD of thelaser beam production module such that the laser beam is producedtherefrom only during those time intervals when the laser beam (asredirected by the rotating polygon 36) provides the uni-directionalsingle line scan (e.g., strikes the central stationary mirror 38C) asspecified by the pulses of the timing signal T_(SLS). However, the VLDduty cycle control circuit 635 operates, under control of the controlcircuitry 611A in the omni-directional (multiple scan line) scan mode ofoperation, to control the duty cycle of the VLD of the laser beamproduction module such that the laser beam is produced continuouslytherefrom to thereby produce the omni-directional multiple line scan asdiscussed above. An example of Boolean logic expressions thatselectively enable the VLD drive circuitry of the scanning circuit 613to provide such VLD duty cycle control is illustrated in FIG. 7C. Thefirst term provides the enablement of the VLD drive circuitry in theunidirectional (single scan line) scan mode of operation (which isdictated by the control circuitry 611A with signals E₁₀=1 and A₅=1). Thesecond term provides the enablement of the VLD drive circuitry in theomni-directional (multiple scan line) scan mode of operation (which isdictated by the control circuitry 611A with signals E₁₀=1 and A₅=0).

[0127] In the illustrative embodiment, the system control operationsperformed by the control circuitry 611A and the control module 611Bselectively enable either: i) the scanning circuit 613, scanphotoreceiving circuit 615, SOS photoreceiving circuit 631, timingsignal generator circuit 633 and VLD duty cycle control circuit 635using enable signal E₁₀=1, or ii) object detect circuitry 629 (andobject sensing circuitry 627 indirectly) using enable signal E₁=1; whileproviding only biasing voltages to all other system components.Advantageously, this control strategy ensures that the scanning circuit613, scan photoreceiving circuit 615, SOS photoreceiving circuit 631 andthe object sensing circuit 627 are not active at the same time.Generally, it would be disadvantageous to do so because the wavelengthof the infrared LED of the object sensing circuit 627 typically fallswithin the optical input spectrum of the scan photoreceiving circuit 615and SOS photoreceiving circuit 631. In addition, less power is consumedwhen either set of components is inactive (i.e. disabled).

[0128] An illustrative embodiment of the SOS photoreceiving circuit 631and timing signal generator 633 is shown in FIG. 7D. The SOSphotoreceiving 631 includes a photodetector Dl and associated biascircuitry that detects the laser light directed thereto by thepositioning indicating optical element(s) of the scanning platform (suchas a lens and light guide or mirror as described above) and produces ananalog electrical signal which is proportional to the intensity of thedetected laser light. This analog signal is supplied to a comparator(LM2903), which switches logic states from a high level to a low leveland then back in response to large signal variations (pulses) in theelectrical signal produced by the photodetector to thereby generate thetiming signal T_(SOS) as shown in FIG. 7A. The timing signal generator633 includes a 555 timer circuit configured for mono-stable (one-shot)operation as is well known in the art, which includes the following pindescriptions:

[0129] Pin 1—Ground

[0130] Pin 2—Trigger

[0131] Pin 3—Output

[0132] Pin 4—Reset

[0133] Pin 5—Control Voltage

[0134] Pin 6—Threshold

[0135] Pin 7—Discharge

[0136] Pin 8—V+

[0137] In this configuration, the timing signal T_(SOS) is supplied tothe trigger input (pin 2) of the 555 timer, which provides a delay pulseat its output (pin 3) that is coincident to the input pulse supplied viathe trigger input and whose duration is controlled by the values ofexternal resistor R and capacitor C (e.g., delay interval=1.1 *R*C).Thus, such R,C values are selected to correspond to the time duration(e.g. the time period between T₂ and T₁ in FIG. 7B) that the scanningbeam (as redirected by the rotating polygon) strikes the other mirrors(and does not strike the particular mirror group, e.g., centralstationary mirror 38C, that provides the unidirectional single scanline). When configured in this manner, the 555 timer generates thetiming signal T_(SLS) as shown in FIG. 7B.

[0138] As described above, the timing signal T_(SLS) is provided to VLDduty cycle control circuit 635, which operates, under control of thecontrol circuitry 611A in the uni-directional (single scan line) scanmode of operation, to control the duty cycle of the VLD of the laserbeam production module such that the laser beam is produced therefromonly during those time intervals when the laser beam (as redirected bythe rotating polygon 36) provides the unidirectional single line scan(e.g., strikes the central stationary mirror 38C) as specified by thepulses of the timing signal T_(SLS). The VLD duty cycle control circuit635 operates, under control of the control circuitry 611A in theomni-directional (multiple scan line) scan mode of operation, to controlthe duty cycle of the VLD of the laser beam production module such thatthe laser beam is produced continuously therefrom to thereby produce theomni-directional multiple line scan as discussed above. An example ofBoolean logic expressions that selectively enable the VLD drivecircuitry of the scanning circuit 613 to provide such VLD duty cyclecontrol is illustrated in FIG. 7C. The first term provides theenablement of the VLD drive circuitry in the uni-directional (singlescan line) scan mode of operation (which is dictated by the controlcircuitry 611A with signals E₁₀=1 and A₅=1). The second term providesthe enablement of the VLD drive circuitry in the omni-directional(multiple scan line) scan mode of operation (which is dictated by thecontrol circuitry 611A with signals E₁₀=1 and A₅=0).

[0139] In an alternate embodiment of the present invention, the timingsignal(s) synchronized to the time interval when the laser beam (asredirected by the rotating polygon 36) provides the unidirectionalsingle line scan (e.g., strikes the central stationary mirror 38C), suchas timing signal T_(SLS) as set forth above, may be used to control thepower level of the laser light source of the laser beam productionmodule in the single line scan mode of operation such that:

[0140] i) the output power of the laser beam produced therefrom is setto the normal output power when the laser beam (as redirected by therotating polygon 36) strikes the mirror(s) that provide theuni-directional signal line scan (e.g., the central stationary mirror38C); and

[0141] ii) the output power of the laser beam produced therefrom issignificantly less than normal output power (for example, {fraction(1/50)}th of the output power of the laser beam during normal operation)when the laser beam (as redirected by the rotating polygon 36) strikesthe mirrors that are not used to provide the uni-directional signal linescan (e.g., the mirrors other than the central stationary mirror 38C).

[0142]FIG. 7E is a schematic diagram of an illustrative embodiment ofcircuitry 635′ that utilizes such timing signals to control the powerlevel of a laser light source (e.g., VLD). In this illustrativeembodiment, the scanning platform includes a VLD module 651 with a laserdiode 653 and integral monitor photodiode 655. As is well known in theart, VLD Drive Circuitry 657 utilizes the current produced by themonitor photodiode 655 as feedback to control the power of the laserdiode 653 (i.e., the amount of current supplied to the laser diode 653)such that the laser diode operates in a suitable operating range. Thecurrent produced by the monitor photodiode 655 and the correspondingoptical power produced by the laser diode 653 is set by the value ofbias resistance operably coupled to VLD Drive circuitry 657. Morespecifically, the optical power produced by the laser diode 653 isinversely proportional to the value of such bias resistance. A biasresistance value, which is denoted R_(SBT) for the sake of description,that produces a laser beam with normal output power characteristics isselected by testing of the system.

[0143] Circuitry 635′ operates during the single scan line mode ofoperation (e.g., when the scanning device is removed from its supportingbase unit and the mode select switch is open) to vary the effective biasresistance provided to the VLD Drive circuitry 657 in response to logiclevel variations of the timing signal supplied thereto (e.g., timingsignal T_(SLS)) to control the output power level of the laser diode 653as follows:

[0144] i) when the laser beam (as redirected by the rotating polygon 36)strikes the mirror(s) that provide the unidirectional signal line scan(e.g., the central stationary mirror 38C), the effective bias resistanceprovided to the VLD Drive circuitry 657 is approximately R_(SBT), whichsets the output power of the laser beam produced by the laser diode 653to the normal output power; and

[0145] ii) when the laser beam (as redirected by the rotating polygon36) strikes the mirror(s) that are not used to provide theunidirectional signal line scan (e.g., the mirrors other than thecentral stationary mirror 38C), the effective bias resistance providedto the VLD Drive circuitry 657 is approximately 50* R_(SBT), which setsthe output power of the laser beam produced by the laser diode 653 to besignificantly less than the output power during normal operation (inthis example, {fraction (1/50)}th of the output power of the laser beamduring normal operation); such operation produces multiple low power“dim” laser scanning lines that scan the scanning field.

[0146] Circuitry 635′ operates during the omni-directional scan mode ofoperation (e.g., when the scanner housing is placed in its supportingbase unit and the mode select switch is closed) to provide a biasresistance to the VLD Drive circuitry 657 (that does not vary inresponse to logic level variations of the timing signal supplied thereto(e.g., timing signal T_(SLS)) that is approximately R_(SBT), which setsthe output power of the laser beam produced by the laser diode 653 tonormal output power during the full rotation of the scanning element.Such operation produces multiple normal power laser scanning lines thatscan the scanning field.

[0147] As shown in FIG. 7E, circuit 635′ includes a FET transistor Q1(configured as an inverter) whose input is operably coupled to thetiming signal T_(SLS) (generated by the timing signal generator) and themode select switch. The output of Q1 is coupled to gate of second FETtransistor Q2. The output of Q2 is coupled to the intermediary nodebetween two resistors coupled in series between the VLD Drive circuitry657 and signal ground. One of these resistors has a resistance R_(SBT)and the other resistor has a resistance 50*R_(SBT) as shown. The ON/OFFoperation of Q2 controls the effective bias resistance supplied to theVLD drive circuitry, and thus the optical power of the laser diode 653.

[0148] As shown in the table of FIG. 7E, when Q1 is OFF, Q2 is ON andthe effective bias resistance provided to the VLD Drive circuitry isapproximately R_(SBT). This sets the output power of the laser beamproduced by the laser diode 653 to the normal output power. Yet, when Q1is ON, Q2 is OFF and the effective bias resistance provided to the VLDDrive circuitry is approximately 51R_(SBT) (R_(SBT)+50*R_(SBT)). Thissets the output power of the laser beam produced by the laser diode 653to be significantly less than the output power during normal operation(in this example, {fraction (1/50)}th of the output power of the laserbeam during normal operation).

[0149] In addition, the table of FIG. 7E shows the interaction of themode select switch and the logic levels of the timing signal T_(SLS) inconjunction with the ON/OFF state of FET transistors Q1 and Q2 incontrolling the effective bias resistance supplied to the VLD Drivecircuitry 657 during the single line scan mode of operation (e.g., whenthe scanner housing is removed from its supporting base unit and themode select switch is open) and during the omni-directional scan mode ofoperation (e.g., when the scanner housing is placed in its supportingbase unit and the mode select switch is closed).

[0150] Referring to FIG. 8, the automatically-activated hand-supportablebar code reading device of the present invention has four basic statesof operation namely: object detection, bar code symbol presencedetection, bar code symbol reading, and symbol character datatransmission (which is shown as 3 states: Data Packet Synthesis, DataPacket Transmission and End of Data Transmission). The nature of each ofthese states is described above in great detail.

[0151] Transitions between the various states are indicated bydirectional arrows. Besides each set of directional arrows aretransition conditions expressed in terms of control activation signals(e.g. A₁, A₂, A₃, A₅) and where appropriate, state time intervals (e.g.T₁). In the illustrative embodiment depicted by the state diagram ofFIG. 8, the automatically-activated hand-supportable bar code readingdevice is powered-up and automatically enters the bar code symbolpresence detect state. Upon detecting a bar code symbol and successfullyreading the bar code symbol in the bar code reading state, the deviceautomatically enters the data transmission state (upon occurrence of theprescribed conditions) to transmit the symbol character datacorresponding thereto to the host system. Upon completion of such datatransmission, the device returns to the bar code symbol presence detectstate to attempt to detect/read/transmit additional bar code symbols inits scanning field. Conveniently, the state diagram of FIG. 8 expressesmost simply the four basic operations occurring during the control flowwithin the system control program of FIGS. 9A to 9D. Significantly, thecontrol activation signals A₁, A₂, A₃, A4 and A₅ in FIG. 8 indicatewhich events within the object detection and/or bar codedetection/reading states can operate to effect a state transition withinthe allotted time frame(s), where prescribed.

[0152]FIGS. 9A, 9B, 9C and 9D, taken together, show a high level flowchart of an exemplary control process carried out by the controlsubsystem of the bar code reading device 151′ of FIG. 6 during thecourse of its programmed operation. Notably, in system control processshown in FIGS. 9A to 9D, it has been assumed that the system employs aone-way RF data communication link between the bar code symbol readingdevice and its associated base unit, as shown in FIG. 6. It isunderstood that alternative data communication links, based on 1-way and2-way RF principles alike, can be used with excellent results.

[0153] Beginning at block A of FIG. 9A, the bar code symbol readingdevice is “initialized”. This initialization step involves severalsteps, including: activating (i.e. enabling) control circuitry 611A andcontrol module 611B, clearing all timers (T₁, T₂, T₃), and clearing thesymbol decode data buffer.

[0154] In block B, control circuitry 611A activates the scanningplatform (e.g., scan photoreceiving circuit 615, A/D conversioncircuitry 317, SOS photoreceiving circuit 631, timing signal generatorcircuit 633, VLD duty cycle control circuit 635 and scanning circuit613) by producing E₁₀=1. In addition, the control circuitry 611A enablesbar code symbol presence detect circuitry 619 by producing E₂=1. Controlmodule 611B drives a visible indicator (one or more of lights 170′) thatindicates the laser is ON (which remains ON during bar code symbolpresence detect operations and bar code symbol reading operations).

[0155] In Block C, control circuitry 611A resets and starts Timer T₁,permitting it to run for a predetermined time period T₁ max (which maybe, for example, 10 seconds).

[0156] In block D, the control circuitry 611A checks to determinewhether the Timer T₁ has expired (i.e., T₁>T₁ max). If not, theoperation returns to block E. If so, the operation continues to block Xas shown in FIG. 9D to perform object detection.

[0157] In Block E, the control circuitry 611A checks to determinewhether it has received control activation signal A₂=1 from the bar codesymbol presence detect circuitry 619 (indicating the presence of a barcode symbol in the scanning field). The operations of blocks D and Ethus determine whether control circuitry 611A has received controlactivation signal A₂=1 within the time period T₁ max. If this signal isreceived within the prescribed time period, the operation continues toblock F; otherwise the operation returns to block D.

[0158] In block F, the control module 611B activates the bar code symbolreading module 621 (for example, by producing E₃=1) and resets andstarts Timer T₂, permitting it to run for a predetermined time period T₂max (which may be, for example, 3 seconds).

[0159] In block G, the control module 611B checks to determine whetherthe Timer T₂ has expired (i.e., T₂>T₂ max). If not, the operationcontinues to block H. If so, the operation returns to block C to performbar code symbol presence detection operations.

[0160] In Block H, the control module 611B checks to determine whetherit has received control activation signal A₃=1 from the bar code symbolreading module 621 (indicating the successful reading of a bar codesymbol in the scanning field). The operations of blocks G and H thusdetermine whether control module 611B has received control activationsignal A₃=1 within the time period T₂ max. If this signal is receivedwithin the prescribed time period, the operation continues to block I ofFIG. 9B; otherwise the operation returns to block G.

[0161] Referring to FIG. 9B, in block I, the control module 611B drivesa visible indicator (one or more of the lights 170′) that indicatessuccessful reading of a bar code symbol and operation continues to blockJ.

[0162] In block J, the control module 611B checks whether it hasreceived either control activation signal A₄=1 from the datatransmission switch 637 (indicating the activation of the datatransmission switch), or control activation signal A₅=0 from the modeselect switch 639 (indicating omni-directional scan mode). Theoperations of blocks G,H, and J thus determine whether the controlactivation signal A₃=1 and (activation signal A₄=1 or control activationsignal A₅=0 ) have been received within the time period T₂ max. If thiscondition is met, the operation continues to block K; otherwise theoperation returns to block G to continue bar code symbol readingoperations.

[0163] In block K, the control module 611B checks whether the symboldecode buffer is zeroed. If so, the operation continues to block P;otherwise the operation continues to block L.

[0164] In Block L, the control module 611B checks whether the bar codesymbol decoded by the bar code symbol reading module 621 is differentthan the bar code symbol in the symbol decode buffer. If so, theoperation continues to block P; otherwise the operation continues toblock M.

[0165] In Block M, the control module 611B resets and starts Timer T₃ ifa status flag (T3 Flag) indicates that Timer T₃ is “NOT RUNNING” andsets this status flag to “RUNNING”. In block N, the control module 611Bchecks to determine whether the Timer T₃ has expired (i.e., T₃>T₃ max).If not, the operation returns to block C to perform bar code symbolpresence detect operations. If so, the operation continues to block owherein the symbol decode data buffer is zeroed, the timer T₃ isstopped, and the status flag is set to “NOT RUNNING”, and the operationreturns to block C. The operations of blocks L,M, N and o is designed toidentify the situation where the same bar code is read by the systemover successive reading periods, and disable the transmission of thesubsequently read bar code symbols until a waiting period (bounded bytimer T₃) has expired)

[0166] In block P, the control module 611B stores the bar code symboldata generated by the bar code symbol reading module 621 in the symboldecode data buffer, deactivates the bar code symbol reading module 621,clears the indicating successful reading of a bar code symbol, anddrives a visual indicator (e.g., one or more of lights 170′) indicatingdata transmission.

[0167] In block Q, the control module 611B activates the data packetsynthesis module 623 and data packet transmission circuit 625 andoperates in blocks R though W to transmit a predetermined number of Npackets that contain such bar code symbol data stored in the symboldecode data buffer to the base unit 503, which communicates suchinformation to the host system operably coupled thereto.

[0168] In block R, the data packet synthesis module 623 operates, undercontrol of control module 611B, to set a packet number to 1.

[0169] Referring to FIG. 9C, in block S, the data packet synthesismodule 623 operates, under control of control module 611B, to constructa data packet that contains the symbol character data as wells as atransmitter number, data packet number, error detection and correctiondata and framing characters.

[0170] In block T, the data packet synthesis module 623 outputs the datapacket constructed in block S to the data transmission circuit 625, fortransmission to the base unit 503, which communicates such informationto the host system. Thereafter, the data packet transmission circuit 625transmits this data packet to the base unit 503, which communicates suchinformation to the host system.

[0171] In block U, the data packet synthesis module 623 checks whetherit has constructed and output the N packets that represent the symbolcharacter data stored in the symbol decode data buffer. If so, theoperation continues to block V wherein the control module 611B clearsthe data transmission indicator and deactivates the data packetsynthesis module 623 and the data transmission circuit 625.

[0172] If in block U, the data packet synthesis module 623 determinesthe it has not completed constructed and output of the N packets, itincrements the data packet number and returns to block S to continueconstruction and output of the next data packet.

[0173] Referring to FIG. 9D, the control operations of the object detectstate are described in blocks X through AA. In block X, the controlcircuitry 611A deactivates the scanning platform (e.g., scanphotoreceiving circuit 615, A/D conversion circuitry 317, SOSphotoreceiving circuit 631, timing signal generator circuit 633, VLDduty cycle control circuit 635 and scanning circuit 613) by producingE₁₀=0. In addition, the control circuitry 611A disables bar code symbolpresence detect circuitry 619 by producing E₂=0, and control module 611Bclears the visible indicator that indicates the laser is ON.

[0174] In block Y, the control circuitry 611A activates the objectdetection subsystem (circuitry 627 and 629) by producing E₁=1, andcontrol module 611B drives the visible indicator (e.g., one of thelights 170′) that indicates the device is performing object detectionoperations.

[0175] In block Z, the control circuitry 611A checks to determinewhether it has received control activation signal A₁=1 from the objectdetect circuitry 629 (indicating the presence of an object in the objectdetect field). If this signal is received, the operation continues toblock AA; otherwise the operation returns to block Z to continue theobject detection operations.

[0176] In block AA, the control circuitry deactivates the objectdetection subsystem (circuitry 627 and 629) by producing E₁=0, andcontrol module 611B clears the visible indicator that indicates thedevice is performing object detection operations, and operationcontinues to block B as shown in FIG. 9A to perform bar code symboldetection and bar code symbol reading operations.

[0177] It should be noted that the object detection subsystem, theobject detect state, and the corresponding object detection operationsperformed in the object detect state as described above may be omitted.In such a system, instead of entering the object detect mode, the deviceis controlled to enter a sleep mode wherein much of the activecomponents of the device are turned off (for power savings). In thissleep mode, the device automatically transitions into the bar codesymbol presence detect state after a predetermined sleep period.

[0178] In addition, it should be noted that the control process carriedout by the control subsystem of the bar code reading device 151′ of FIG.6 during the course of its programmed operation as set forth above maybe varied significantly without departing from the scope of theinventions as described earlier herein.

[0179] Examples of such variations in control are described in detail inU.S. Pat. No. 6,283,375 to Wilz et al., incorporated by reference abovein its entirety. In another exemplary variation, the control subsystemcan be programmed to enable a user to selectively operate thehand-holdable bar code scanning device in the unidirectional single linescan mode while the scanning device rests in its support stand. Suchuser control may be provided via user interaction with the datatransmission activation switch 637. For example, the control subsystemcan be programmed to monitor the status of control activation signals A₄and A₅ produced by the data transmission switch and mode select switch,respectively. In the event that the control subsystem detects thepresence of control activation signal A₅=0 (indicating the hand-holdablebar code scanning device rests in its support stand) in addition tocontrol activation signal A₄=1 (indicating the activation of the datatransmission switch), the control subsystem can switch into theunidirectional single line bar code scanning/reading mode (and enablethe operations performed therein) as described above when the datatransmission switch is deactivated (e.g., transition to controlactivation signal A₄=0). Such single line bar code scanning operationspreferably involve controlling the duty cycle (or power level) of thelaser light source to enable unidirectional single line bar codescanning as described above.

[0180] Additional Features

[0181] In the illustrative embodiments described above, the spectraltransmission characteristics of the light transmission window 168 of thebar code symbol reading device are preferably tuned to thecharacteristic wavelength range of the light source(s) used for scanningand object detection such that wavelengths close to this characteristicwavelength range are permitted to exit and enter the interior volume ofthe housing with minimum attenuation, while wavelengths substantiallyless than this characteristic wavelength range(and/or wavelengthssubstantially greater than this characteristic wavelength range) are notpermitted to exit and enter the interior volume of the housing (i.e.,provides substantial attenuation of such wavelengths). For example,consider the case where the light source used for scanning is a VLD witha characteristic wavelength range centered around 670 nanometers andwhere the light source used for object detection is an infra-red LEDwith a characteristic wavelength centered around 870 nanometers, thespectral transmission characteristics of the light transmission windowmay be tuned such that all wavelengths greater (i.e. longer) thanslightly less than 670 nm (e.g. longer than 665 nm) are permitted toexit and enter the interior volume of the housing with minimumattenuation. As a result of such characteristics, the scans lines (at670 nanometers) and the infra-red (IR) light (at about 870 nm) areallowed to propagate through the transmission window 168, reflect froman object/bar code surface, and return through the transmission window,while minimizing the propagation of spectral noise from light sourcesoutside this band (e.g., having wavelengths less than 665 nm) throughthe window, thereby improving the signal-to-noise ratio of the scanningengine.

[0182] Similarly, an optical filter having transmission characteristicstuned to the characteristic wavelength range of the light source usedfor scanning may be mounted in front of the detector of the scanningengine (e.g., the detector 41 of the scanning platform of FIGS. 4A to4D2) such that wavelengths close to this characteristic wavelength rangeare permitted to exit and enter the interior volume of the housing withminimum attenuation, while wavelengths substantially less than thischaracteristic wavelength range(and/or wavelengths substantially greaterthan this characteristic wavelength range) are not permitted to exit andenter the interior volume of the housing (i.e., provides substantialattenuation of such wavelengths). This minimizes the spectral noise fromlight sources outside this band (e.g., having wavelengths less than 665nm) that are incident on the detector, thereby improving thesignal-to-noise ratio of the scanning engine.

[0183] The details of such optical filtering arrangements are disclosedin U.S. Pat. No. 5,627,359 to Amundsen et al., commonly assigned toassignee of the present application, herein incorporated by reference inits entirety.

[0184] It is understood that the automatically-activated hand-holdablebar code reading systems and methods of the illustrative embodimentsdescribed hereinabove may be modified in a variety of ways which willbecome readily apparent to those skilled in the art of having thebenefit of the novel teachings disclosed herein. All such modificationsand variations of the illustrative embodiments thereof shall be deemedto be within the scope and spirit of the present invention as defined bythe claims to Invention appended hereto,

What is claimed is:
 1. A bar code symbol reading device comprising: (1)a hand-supportable housing having a light transmission aperture throughwhich visible light can exit and enter said hand-supportable housing;(2) a laser scanning engine, disposed within said hand supportablehousing, that selectively operates in one of first and second scanmodes, wherein in said first scan mode, the laser scanning engineprojects an omni-directional scan pattern through said lighttransmission aperture, detects and decodes bar code symbols on objectspassing through said omni-directional scan pattern, and produces symbolcharacter data representative of decoded bar code symbols, and whereinin said second scan mode the laser scanning engine projects a singleline scan pattern through said light transmission aperture and detectsand decodes bar code symbols on objects passing through said single linescan pattern, and produces symbol character data representative ofdecoded bar code symbols, (3) a manually-activated data transmissionswitch integrated with said hand-supportable housing, for producing adata transmission activation control signal in response to activation ofthe data transmission switch; (4) a data transmission subsystem in saidhand-supportable housing that operates under control of controlcircuitry to communicate the symbol character data produced by the laserscanning engine to a host device operably coupled to said bar codesymbol reading device; (5) said control circuitry enabling communicationof symbol character data produced by the laser scanning engine in saidsecond scan mode of operation to said host device upon occurrence of afirst set of predetermined conditions including receipt of said datatransmission activation control signal produced by said datatransmission switch, and said control circuitry disabling communicationof symbol character data produced by the laser scanning engine in saidsecond scan mode of operation to said host device upon occurrence of asecond set of predetermined conditions including lack of receipt of saiddata transmission activation control signal produced by said datatransmission switch.
 2. The bar code symbol reading device of claim 1,wherein said control circuitry enables communication of symbol characterdata produced by the laser scanning engine in said first scan mode ofoperation to said host device irrespective of said data transmissionactivation control signal produced by said data transmission switch. 3.The bar code symbol reading device of claim 1, further comprising asupport stand that supports said hand-supportable housing, and modeselection means integrated with said hand-supportable housing, forselectively operating said laser scanning engine in one of said firstand second scan modes in response to placement of said hand-supportablehousing in said support stand.
 4. The bar code symbol reading device ofclaim 1, wherein said laser scanning engine comprises: a bar code symbolpresence detection means in said hand-supportable housing for processingscan data so as to detect the presence of said bar code symbol on saidobject and to automatically generate a first control signal in responseto the detection of said bar code symbol; and decode processing means insaid hand-supportable housing for processing scan data so as to decodesaid bar code symbol on said object and for automatically producingsymbol character data representative of said decoded bar code symbol,and automatically generating a second control signal indicative of theproduction of said symbol character data.
 5. The bar code symbol readingdevice of claim 4, wherein said bar code symbol presence detection meansdetects said bar code symbol by detecting first and second envelopeborders of said bar code symbol.
 6. The bar code symbol reading deviceof claim 4, wherein said first set of predetermined conditions includesreceipt of said second control signal and said data transmissionactivation control signal within respective predetermined time periods,and said second set of predetermined conditions includes receipt of saidsecond control signal and lack of receipt of said data transmissionactivation control signal within respective predetermined time periods.7. The bar code symbol reading device of claim 4, wherein said laserscanning engine comprises object detection means in saidhand-supportable housing, for detecting said object in at least aportion of an object detection field defined relative to said housingand automatically generating a third control signal indicative of thedetection of said object in at least a portion of said object detectionfield.
 8. The bar code symbol reading device of claim 7, furthercomprising control circuitry that selectively activates said bar codesymbol presence detection means and said decode processing means inresponse to occurrence of said third control signal.
 9. The bar codesymbol reading device of claim 7, wherein said object detection meanscomprises: a signal transmitting means for transmitting a signal towardssaid object in said object detection field, and a signal receiving meansfor receiving said transmitted signal reflected off said object in atleast a portion of said object detection field, and automaticallygenerating said third control signal indicative of the detection of saidobject in at least a portion of said object detection field.
 10. The barcode symbol reading device of claim 9, wherein said signal transmittingmeans comprises an infra-red light source for transmitting a pulsedinfra-red light signal, and wherein said signal receiving meanscomprises an infra-red light detector disposed in said hand-supportablehousing.
 11. The bar code symbol reading device of claim 9, wherein saidsignal transmitting means comprises a laser diode for transmitting apulsed laser signal, and wherein said signal receiving means comprises aphotodetector disposed in said hand-supportable housing.
 12. The barcode symbol reading device of claim 1, wherein said laser scanningengine comprises a visible laser light source, a scanning element and atleast one stationary mirror that cooperate to project said single linescan pattern through said light transmission aperture in said secondscan mode.
 13. The bar code symbol reading device of claim 1, whereinsaid laser scanning engine comprises a visible laser light source, ascanning element and a plurality of stationary mirrors that cooperate toproject said omni-directional scan pattern through said lighttransmission aperture in said first scan mode.
 14. The bar code symbolreading device of claim 13, wherein said visible laser light source,scanning element and a predetermined subset of said plurality ofstationary mirrors of the laser scanning engine cooperate to projectsaid single line scan pattern through said light transmission aperturein said second scan mode.
 15. The bar code symbol reading device ofclaim 14, further comprising control circuitry that operates, in saidsecond scan mode, to control power of said visible laser light producedby said laser light source.
 16. The bar code symbol reading device ofclaim 15, wherein said control circuitry operates, in said second scanmode, to control the duty cycle of said visible laser light toselectively enable said laser light source to produce laser light onlywhen the light produced therefrom is directed by said scanning elementonto said predetermined subset of stationary mirrors.
 17. The bar codesymbol reading device of claim 15, wherein said control circuitryoperates, in said second scan mode, to control power of said visiblelaser light such that: said laser light source produces normal powerlaser light when the light produced therefrom is directed by saidscanning element onto said predetermined subset of stationary mirrors,and said laser light source produces significantly lower power laserlight when the light produced therefrom is not directed by said scanningelement onto said predetermined subset of stationary mirrors.
 18. Thebar code symbol reading device of claim 15, wherein said scanningelement comprises a rotating light directing element having a rotationcycle and said control circuitry derives timing signals synchronized toa particular interval in the rotation cycle of said rotating lightdirecting element wherein the rotating light directing element directslight produced from the laser light source onto said predeterminedsubset of stationary mirrors.
 19. The bar code symbol reading device ofclaim 18, wherein said timing signals are derived from a position sensorintegrated into a rotating portion of the rotating light directingelement.
 20. The bar code symbol reading device of claim 18, whereinsaid timing signals are derived from a position indicating opticalelement mounted adjacent (or near) the perimeter of one of saidstationary mirrors, such that the position indicating optical element isilluminated by light produced from said laser light source when therotating light directing element reaches a predetermined point in itsrotation.
 21. The bar code symbol reading device of claim 20, whereinsaid position indicating optical element comprises a mirror that directsillumination incident thereon to a position indicating optical detector,which generates an electrical signal whose amplitude corresponds to theintensity of light incident thereon.
 22. The bar code symbol readingdevice of claim 20, wherein said position indicating optical elementcomprises a light collecting lens that is operably coupled to a lightguide to direct illumination incident on the light collecting lens to aposition indicating optical detector, which generates an electricalsignal whose amplitude corresponds to the intensity of light incidentthereon.
 23. The bar code symbol reading device of claim 22, whereinsaid light guide comprises a fiber optic bundle.
 24. The bar code symbolreading device of claim 15, wherein said control circuitry comprises a555 timer integrated circuit configured for mono-stable operation. 25.The bar code symbol reading device of claim 1, wherein said laserscanning engine operates in a preprogrammed set of operational stateswherethrough the laser scanning engine automatically passes during eachbar code symbol reading operation.
 26. The bar code symbol readingdevice of claim 25, wherein the preprogrammed set of operational statesinclude a bar code presence detection state of operation and a bar codesymbol reading state of operation.
 27. The bar code symbol readingdevice of claim 26, wherein the preprogrammed set of operational statesfurther include an object detection state of operation.
 28. The bar codesymbol reading device of claim 27, which further comprises an objectiondetection subsystem realized using either infrared (IR) signaltransmission/receiving technology, or low-power non-visible laser beamsignaling technology, for automatically detecting an object within anobject detection field defined relative to said hand-supportablehousing.
 29. The bar code symbol reading device of claim 1, furthercomprising a set of color-encoded light sources provide on the exteriorof said hand-supportable housing for sequentially generating a set ofvisually-perceptible state indication signals that visually indicate tothe user the various states of operation, wherethrough said deviceautomatically passes during each instance of automatic bar code symbolreading in accordance with the present invention.
 30. The bar codesymbol reading device of claim 3, wherein said device, when placed insaid support stand, operates in said first scan mode of operation as astationary hands-free projection scanner, and wherein said device, whenremoved from said support stand, operates in said second scan mode ofoperation as a portable hand-held scanner.
 31. A method of transmittingbar code symbol character data to a host computer system, said methodcomprising the steps of: controlling a laser scanning engine disposedwithin a hand-supportable housing to selectively operate in one of firstand second scan modes, wherein in said first scan mode, the laserscanning engine projects an omni-directional scan pattern through alight transmission aperture, detects and decodes bar code symbols onobjects passing through said omni-directional scan pattern, and producessymbol character data representative of decoded bar code symbols, andwherein in said second scan mode the laser scanning engine projects asingle line scan pattern through said light transmission aperture anddetects and decodes bar code symbols on objects passing through saidsingle line scan pattern, and produces symbol character datarepresentative of decoded bar code symbols, producing a datatransmission activation control signal in response to themanual-actuation of a manually-actuatable data transmission switch;enabling communication of symbol character data produced by the laserscanning engine in said second scan mode of operation to said hostdevice upon occurrence of a first set of predetermined conditionsincluding receipt of said data transmission activation control signalproduced by said data transmission switch; disabling communication ofsymbol character data produced by the laser scanning engine in saidsecond scan mode of operation to said host device upon occurrence of asecond set of predetermined conditions including lack of receipt of saiddata transmission activation control signal produced by said datatransmission switch.
 32. The method of claim 31, further comprising thestep of enabling communication of symbol character data produced by thelaser scanning engine in said first scan mode of operation to said hostdevice irrespective of said data transmission activation control signalproduced by said data transmission switch.
 33. The method of claim 31,wherein the enabling step is performed at least in part by a programmedcontroller.
 34. The method of claim 31, wherein the laser scanningengine is selectively operated in one of said first and second scanmodes in response to placement of said hand-supportable housing in asupport stand that supports said hand-supportable housing.
 35. Themethod of claim 31, further comprising the step of controlling the laserscanning engine to operate in a preprogrammed set of operational stateswherethrough the laser scanning engine automatically passes during eachbar code symbol reading operation.
 36. The method of claim 35, whereinthe preprogrammed set of operational states include a bar code presencedetection state of operation and a bar code symbol reading state ofoperation.
 37. The method of claim 36, wherein said laser scanningengine comprises: bar code symbol presence detection means forprocessing scan data so as to detect the presence of said bar codesymbol on said object and to automatically generate a first controlsignal in response to the detection of said bar code symbol; and decodeprocessing means in said hand-supportable housing for processing scandata so as to decode said bar code symbol on said object and forautomatically producing symbol character data representative of saiddecoded bar code symbol, and automatically generating a second controlsignal indicative of the production of said symbol character data. 38.The method of claim 37, wherein said first set of predeterminedconditions includes receipt of said second control signal and said datatransmission activation control signal within respective predeterminedtime periods, and said second set of predetermined conditions includesreceipt of said second control signal and lack of receipt of said datatransmission activation control signal within respective predeterminedtime periods.
 39. The method of claim 36, wherein the preprogrammed setof operational states further include an object detection state ofoperation.
 40. The method of claim 39, wherein the laser scanning engineutilizes either infrared (IR) signal transmission/receiving technology,or low-power non-visible laser beam signaling technology, forautomatically detecting an object within an object detection fielddefined relative to said hand-supportable housing.
 41. The method ofclaim 39, further comprising the step of selectively operating the laserscanning engine in said bar code symbol presence detection state andsaid bar code symbol reading state in response to operation of the laserscanning engine in said bar code symbol object detection state.
 42. Themethod of claim 31, wherein said laser scanning engine comprises avisible laser light source, a scanning element and at least onestationary mirror that cooperate to project said single line scanpattern through said light transmission aperture in said second scanmode.
 43. The method of claim 31, wherein said laser scanning enginecomprises a visible laser light source, a scanning element and aplurality of stationary mirrors that cooperate to project saidomni-directional scan pattern through said light transmission aperturein said first scan mode.
 44. The method of claim 43, wherein saidvisible laser light source, scanning element and a predetermined subsetof said plurality of stationary mirrors of the laser scanning enginecooperate to project said single line scan pattern through said lighttransmission aperture in said second scan mode.
 45. The method of claim44, further comprising the step of: in said second scan mode,controlling power of said visible laser light produced by said laserlight source.
 46. The method of claim 45, wherein, in said second scanmode, the duty cycle of said visible laser light is controlled toselectively enable said laser light source to produce laser light onlywhen the light produced therefrom is directed by said scanning elementonto said predetermined subset of stationary mirrors.
 47. The method ofclaim 45, wherein, in said second scan mode, power of said visible laserlight is controlled such that: said laser light source produces normalpower laser light when the light produced therefrom is directed by saidscanning element onto said predetermined subset of stationary mirrors,and said laser light source produces significantly lower power laserlight when the light produced therefrom is not directed by said scanningelement onto said predetermined subset of stationary mirrors.
 48. Themethod of claim 45, wherein said scanning element comprises a rotatinglight directing element having a rotation cycle, further comprising thestep of deriving timing signals synchronized to a particular interval inthe rotation cycle of said rotating light directing element wherein therotating light directing element directs light produced from the laserlight source onto said predetermined subset of stationary mirrors. 49.The method of claim 48, wherein said timing signals are derived from aposition sensor integrated into a rotating portion of the rotating lightdirecting element.
 50. The method of claim 48, wherein said timingsignals are derived from a position indicating optical element mountedadjacent (or near) the perimeter of one of said stationary mirrors, suchthat the position indicating optical element is illuminated by lightproduced from said laser light source when the rotating light directingelement reaches a predetermined point in its rotation.
 51. The method ofclaim 50, wherein said position indicating optical element comprises amirror that directs illumination incident thereon to a positionindicating optical detector, which generates an electrical signal whoseamplitude corresponds to the intensity of light incident thereon. 52.The method of claim 50, wherein said position indicating optical elementcomprises a light collecting lens that is operably coupled to a lightguide to direct illumination incident on the light collecting lens to aposition indicating optical detector, which generates an electricalsignal whose amplitude corresponds to the intensity of light incidentthereon.
 53. The method of claim 42, wherein said light guide comprisesa fiber optic bundle.
 54. The method of claim 31, further comprising thestep of: controlling a set of color-encoded light sources provided onthe exterior of said hand-supportable housing to sequentially generate aset of visually-perceptible state indication signals that visuallyindicate to the user the various states of operation during eachinstance of automatic bar code symbol reading in accordance with thepresent invention.